The UN's independent investigator on extrajudicial killings has called on the United States to reveal more details of the raid on Osama bin Laden's Pakistan hideaway to allow experts to assess the legality of his killing.

Pakistan's President acknowledged for the first time on Tuesday that his security forces were left out of a US operation to kill Osama bin Laden, but he did little to dispel questions over how the Al Qaeda leader was able to live in comfort near Islamabad.

Al Qaeda mastermind Osama bin Laden was killed on Sunday in a firefight with US forces deep inside Pakistan, President Barack Obama said, declaring "justice has been done" a decade after the September 11 attacks.

Text of speech: Barack Obama

World's most wanted terrorist was not killed in a cave but in a two-storey house just yards from Pakistan's Military Academy in Abbottabad, a town close to the capital Islamabad, with reports saying that he fired at the US commandos as they swooped down on his hideout.

A hushed silence has descended on the terror groups in their hotbed in Pakistan's lawless tribal belt close to Afghanistan after the slaying of the world's most wanted terrorist Osama bin Laden, with US intelligence saying that militant chatter lines had gone dead.

Ismail Haniya, the head of the Hamas government in the Gaza Strip, on Monday condemned the killing of al Qaeda leader Osama bin Laden in a US raid in Pakistan.

A key World Trade Organisation panel on Monday endorsed Vanuatu's membership bid, paving the way for the Pacific island state's accession to the global free trade system, officials said.

Chancellor Angela Merkel inaugurated Germany's first commercial offshore wind farm on Monday, with 21 turbines set to supply electricity to more than 50,000 households.

West Indies captain Darren Sammy won the toss and elected to field in the fourth one-day International against Pakistan on Monday at Kensington Oval here.