ISLAMABAD - Al Qaeda's South Asia wing has claimed responsibility for hijacking a Pakistani naval ship and trying to use it to fire rockets at U.S. vessels in the Arabian Sea, in the first major assault by the newly created group.

Sources quote its spokesman, Usama Mahmoud, as saying a group of militants had succeeded in seizing control of the Pakistani frigate PNS Zulfiqar and tried to use it to attack nearby U.S. vessels.

"These mujahideen had taken control of the Pakistani ship, and they were advancing towards the American fleet when the Pakistani army stopped them," he said "As a result, the mujahideen, the lions of Allah and benefactors of the Ummah, sacrificed their lives for Allah, and the Pakistani soldiers spoiled their hereafter by giving up their lives in defense of the enemies of the Ummah the Americans."

According to sources Mahmoud's statement also provided a picture and a detailed layout of the PNS Zulfiqar. The navy and the army's press wing were not immediately available for comment.

The naval yard on Pakistan's Arabian Sea coast is a strategically important facility at the centre of U.S.-Pakistani security, anti-terrorism and anti-trafficking cooperation.

The foiled attack comes at a time when regional powers are already concerned about stability as U.S.-led forces continue to withdraw from neighboring Afghanistan, potentially creating a security gap for insurgents to exploit.

The attack, which lasted several hours, also shows just how much the Islamist militants are capable of striking at the heart of Pakistan's vast security apparatus and raises questions about the nuclear-armed nation's ability to guard its installations.

The Pakistani Taliban, closely allied with al Qaeda, had earlier said that the Sept. 6 attack was carried out with the help of insiders. Pakistan later arrested a number of navy personnel on suspicion of collaborating with the attackers.

Al Qaeda announced the formation of the new group on Sept. 4, with its chief, Ayman al-Zawahri, promising to spread Islamic rule and "raise the flag of jihad" across South Asia, home to more than 400 million Muslims.

Analysts say the move is part of al Qaeda's plan to take advantage of the planned withdrawal of U.S.-led forces from Afghanistan and boost its influence in the Afghanistan-Pakistan region as well as India.

It also comes against the backdrop of a full-scale operation launched by Pakistan's military against Taliban militants in the lawless region of North Waziristan following a deadly attack on the airport in the city of Karachi in June.