SANAA (AFP) - A gunman opened fire inside a Yemen mosque on Friday, killing eight people in the second attack in a month targeting namazis in the ancestral land of Al-Qaeda leader Osama bin Laden. In separate violence, unknown assailants fired rockets at an oil pipeline in the south of the country, witnesses said. "A man opened fire on namazis in a mosque in the village of Kahal," 100 kilometres north of the capital Sanaa, killing eight people and wounding nine, an official told AFP. Weekly Juma prayers were under way in the mosque in Amran province when the shooting happened, said the official. The suspect "is believed to be mentally unbalanced," he added. The official Saba news agency gave a lower death toll, saying seven people were killed in the attack and that 12 were wounded. Three of the injured are in a serious condition, the agency said. Saba earlier said 11 were hurt. Saba identified the suspect as Abdullah Saleh Zaid al-Qahali, 24, and said he had been arrested and was being questioned about the attack. Amran police chief Tahar al-Ashwal told Saba the initial investigation has shown that the shooting was "criminally" motivated and linked to a dispute over a plot of land between the suspect and another man. The man involved in the row was killed in the shooting, Ashwal said. Amran Governor Kahlan Mujahid Abu Shuareb said the gunman used a machine-gun and confessed that he had wanted to kill "everyone". He was arrested as he was reloading his weapon. Shuareb described the attack as a "treacherous crime, which contradicts... the precepts of Islam."On May 2, 18 people - mostly soldiers - were killed when a booby-trapped motorcycle exploded at the entrance to a mosque in the northwestern town of Saada. The army blamed that attack on Shia Zaidi armed men who have been waging a four-year uprising against the government in Saada province, a conflict that has claimed thousands of lives despite efforts to organise peace talks. Meanwhile Friday's rocket attack targeted the oil pipeline linking a refinery and an oil terminal in the southern port city of Aden, witnesses said. The attack, which was not immediately claimed by any group, caused no damage. Yemen, which borders oil powerhouse Saudi Arabia, produces only some 380,000 barrels of crude oil daily. The latest violence came just a day after the authorities announced they had broken up an Al-Qaeda cell in Sanaa and arrested 11 suspects.Al-Qaeda has been blamed for a series of attacks across the country. Yemen, one of the poorest countries on the planet, has battled suspected Al-Qaeda fighters at Washington's behest since the September 11, 2001 attacks in the United States. In October 2000, Al-Qaeda fighters on a small explosives-packed boat attacked American warship the USS Cole off Aden, killing 17 American sailors. Al-Qaeda in Yemen, which calls itself Jund Al-Yemen Brigades, has launched a series of attacks in recent months targeting the US and Italian embassies and a residential complex housing US oil workers. In one of the deadliest attacks against foreigners in recent years, eight Spanish tourists were killed and six wounded last July when a suicide bomber rammed a car packed with explosives into a convoy at an ancient temple in July in the northeastern region of Marib.