The Obama administration has accused Pakistan of illegally modifying U.S.-made missiles to expand its ability to hit land-based targets, a charge promptly rejected by Pakistani Ambassador in Washington. Citing senior administration and Congressional officials, The New York Times made the accusation in a dispatch that also said the altered missiles posed a potential threat to India. The Times said the charge came in late June through an unpublicized diplomatic protest to Prime Minister Yousuf Raza Gilani and other top Pakistani officials. "The accusations are incorrect and based on wrong intelligence," Ambassador Husain Haqqani," while commenting on the Times' dispatch. "We will make sure that the US understands the correct picture and we will fight back periodic efforts to falsely blame Pakistan which remains a critical US ally in fighting terrorism," Ambassador Haqqani said, urging the American media to help Pakistan in its vitally important anti-terrorism efforts and desist from making false accusations. "Instead of false accusations, US media should help Pakistan secure the help it needs to fight our common enemy viz; terrorism," he added. The accusation, made amid growing concerns about Pakistan's increasingly rapid conventional and nuclear weapons development, triggered a new round of U.S.-Pakistani tensions, the report added. "There's a concerted effort to get these guys to slow down," the newspaper quoted a senior administration official as saying. "Their energies are misdirected," the official added. The accusation comes at a particularly delicate time, when the administration is asking Congress to approve $7.5 billion in aid to Pakistan over the next five years, the dispatch said. Washington, it added, is also pressing Pakistani military to focus its attentions on fighting the Taliban, rather than expanding its nuclear and conventional forces aimed at India. A senior Pakistani official, who spoke to the Times on the condition of anonymity, also rejected the accusation, saying that the missile tested was developed by Pakistan, just as it had modified North Korean designs to build a range of land-based missiles that could strike India, according to the Times. He said that Pakistan had taken the unusual step of agreeing to allow American officials to inspect the countrys Harpoon inventory to prove that it had not violated the law, a step that administration officials praised. U.S. officials said the disputed weapon is a conventional one based on the Harpoon anti-ship missiles that were sold to Pakistan during the Reagan administration as a defensive weapon, the newspaper reported. The accusation stems from U.S. intelligence agencies' detection of a "suspicious" missile test on April 23 which was never announced by the Pakistanis and which appeared to give it a new offensive weapon, the Times said. U.S. military and intelligence officials suspect Pakistan of modifying the Harpoon sold to them in the 1980s, which would violate the Arms Control Export Act. "The focus of our concern is that this is a potential unauthorized modification of a maritime antiship defensive capability to an offensive land-attack missile," another senior administration official told the Times, speaking on condition of anonymity about classified information. "When we have concerns, we act aggressively," the official added. Pakistan denied the charge and said it developed the missile, the Times said. The Times said some experts were also skeptical of the American claims. Robert Hewson, editor of Janes Air-Launched Weapons, a yearbook and Web-based data service, said the Harpoon missile did not have the necessary range for a land-attack missile, which would lend credibility to Pakistani claims that they are developing their own new missile. Moreover, he said, Pakistan already has more modern land-attack missiles that it developed itself or acquired from China. Theyre beyond the need to reverse-engineer old U.S. kit, Hewson said in a telephone interview. Theyre more sophisticated than that. Hewson said the ship-to-shore missile that Pakistan was testing was part of a concerted effort to develop an array of conventional missiles that could be fired from the air, land or sea to address Indias much more formidable conventional missile arsenal.