Islamabad, May 12 (IANS/AKI) Pakistani opposition leader and former prime minister Nawaz Sharif has demanded an independent investigation into Al-Qaeda leader Osama Bin Laden's killing by US forces, as he called his country's government and powerful armed forces too incompetent to carry out the task.

Speaking to reporters in Islamabad Wednesday, he called on the government to form a judicial commission made up of the chief justice of Pakistan, provincial chief justices and the chief justice from the Islamabad high court to conduct the probe.

Pakistan has denied allegations by the US that Osama must have received support from Pakistani officials in order to live so close to Islamabad, the country's capital.

"Pakistan has been diplomatically isolated," Sharif said. "The entire world views Pakistan as a country which harbours terrorists."

An American team of Navy SEALs May 2 flew in from neighbouring Afghanistan aboard assault helicopters to the upscale town of Abbottabad where they killed Osama in the sprawling compound that is located down the road from a top military cadet academy.

Pakistani Prime Minister Yousuf Raza Gilani announced Monday an investigation into how Osama has been able to live with impunity in Abbottabad.

Sharif said Osama's killing has raised many questions, calling the security lapse a matter of great concern.

"Nobody knows how the US helicopters entered into Pakistan, operated for two and half hours and then returned back to Afghanistan without Pakistan's knowledge.

"This shows Pakistan has a flawed defence system. At the same time, Osama lived in Pakistan for so many years and Pakistani intelligence agencies didn't have a clue.

"I think the situation demands for serious inquiry which should investigate everything and then present a report to be used for action taken against those who were responsible for lapses," Sharif said.

Osama's Yemeni wife has claimed the Al-Qaeda chief had lived for five years in the compound in Abbottabad.