Pakistan acknowledged for the first time on Thursday that parts of the Mumbai terrorist attacks were planned on its soil and said that six suspects were being held and awaiting prosecution. The admission amounted to a significant about-face for the Pakistani government, which has long denied that any terrorist attacks against India, its longtime enemy, have originated in Pakistan. Officials said as recently as Monday that they did not have enough evidence to link the Mumbai assault to Pakistan, and there have been signs of internal tensions in Pakistan over cracking down on Lashkar-e-Taiba, the Pakistan-based militant group that India and the United States have deemed responsible for the Nov. 26 attack on India's financial capital. Pakistani officials did not explicitly name Lashkar as the organizer of the attacks on Thursday, but they did single out as suspects two people who are known to be connected to the group. The formal acknowledgment of a Pakistani role came on the final day of a visit to the country by Richard C. Holbrooke, President Obama's special envoy to the region, who raised the issue with top Pakistani government officials, according to an official familiar with the conversations. Though Pakistani officials denied the announcement was linked to Mr. Holbrooke's visit, the Obama administration has made clear that lowering hostilities between India and Pakistan is a crucial part of a regional solution to the war in Afghanistan. India called Pakistan's admission a "positive development," but said that Pakistan must still take steps to dismantle the "infrastructure of terrorism." In Washington, the State Department spokesman, Robert A. Wood, said, "I think it shows that Pakistan is serious about doing what it can to deal with the people that may have perpetrated these attacks." Both India and the United States have put strong pressure on Pakistan for some concession regarding the Mumbai attacks, which American officials feared were distracting Pakistan from the task of battling militants from the Taliban and Al Qaeda who have bases inside Pakistani territory. Despite seemingly overwhelming evidence presented by India, with the help of American and British investigators, top Pakistani officials had repeatedly raised doubts about the identity of the attackers and the links to Pakistan-based militant leaders. Finally, on Thursday, as Mr. Holbrooke left Pakistan for Afghanistan, Rehman Malik, the senior security official in the Interior Ministry, gave the fullest public account so far of Pakistan's investigation. "Some part of the conspiracy has taken place in Pakistan," he said in a televised news briefing. He emphasized Pakistan's commitment to prosecuting the attackers and, unusually for a government official here, expressed solidarity with India. But he was also careful to diffuse blame for the attacks, noting that the tools used by the attackers to organize their plot " cellphone SIM cards, Internet servers " provided links to other countries, however ancillary. "We have gone the extra mile in conducting an investigation on the basis of information provided by India, and we have proved that we are with the Indian people," Mr. Malik said. "According to the initial inquiry report a part of the conspiracy of Mumbai attacks was hatched in Pakistan; however links have been found in other states, including the U.S.A., Austria, Spain, Italy and Russia," he added. A State Department official, who spoke on condition of anonymity because of diplomatic sensitivities, called the Pakistani announcement a "political decision" to ease tensions with India. While saying they did not have enough proof that the perpetrators were Pakistanis, President Asif Ali Zardari and other civilian leaders have expressed a determination to get to the bottom of the Mumbai attacks. Mr. Zardari even offered to send the nation's top intelligence official to India after the attacks occurred. But his outreach to India met strong resistance from Pakistan's powerful intelligence agency and the military. A Defense Department official, who did not want to be named for similar reasons, said the Pakistani decision may have been an effort by the civilian government to "poke a stick" at the Pakistani military and intelligence service, which helped set up Lashkar in the 1980s as a proxy force to challenge India's control of Kashmir, the disputed border region. Indian officials have previously blamed Lashkar for an attack in 2000 on the Red Fort in New Delhi, as well as involvement in an attack on the Indian Parliament in 2001. Pakistan never acknowledged any Lashkar role in those attacks. The group is officially banned, though it has continued to operate openly. Mr. Malik's statements appeared to vindicate many of India's accusations of Pakistani involvement. But he gave no confirmation of Indian claims that elements of the Pakistani security apparatus may also have been involved along with Lashkar. He said that Zaki ur-Rehman Lakhvi, the operational commander of Lashkar, was "under investigation" as the possible mastermind of the Mumbai assault. And he acknowledged allegations that e-mail messages that claimed responsibility for the attacks were created by Zarar Shah, the Lashkar communications coordinator. While confirming much of the account of the attack already pieced together by American, British and Indian investigators, he also described an apparently broader circle of terrorist operators than previously disclosed. He named some of those arrested as a result of the inquiry, including men he identified as Muhammad Ishfaq and Javed Iqbal, who he said was captured after being lured to Pakistan from Spain. Cellphone SIM cards used in the attacks were bought in Austria, while calls over the Internet, using a server in Texas, were paid for in Barcelona, Spain, he said. Mr. Malik identified another co-conspirator as Hammad Amin Sadiq, who, he said, had been traced through telephone records and bank transfers. "He was basically the main operator," Mr. Malik said. He also said that one of the people involved was in Houston, and that he planned to send a team to United States. Only one of the attackers, Ajmal Kasab, survived the Mumbai assault. The Pakistani authorities have already acknowledged that he was of Pakistani origin. But they have yet to ascertain the identities of the other nine attackers because information provided by India was too vague, Mr. Malik said. Pakistan had given Indian officials a list of 30 questions to which investigators were seeking answers, including some relating to the records of conversations between the attackers and their handlers. "We have asked the Indian authorities to share more information so that the culprits could be given strong prosecution," Mr. Malik said. He said he had originally planned to hold the briefing four to five days earlier, but because of some legal matters, he had to postpone it until Thursday. "The timing has nothing to do with Mr. Holbrooke's visit," he said. But Sajjan M. Gohel, director for international security of the Asia Pacific Foundation in London, who has closely followed the Mumbai investigations, said there was no denying that Pakistan had been under pressure from the United States. "This is unprecedented," he said. "It is the first time Pakistan has acknowledged an attack on India has originated on its soil."