In a show of oneness, party leaders issued a resolution saying they shared India's grief, the BBC reported. But they rejected "unsubstantiated allegations made in haste against Pakistan."

India, the report said, has not directly accused the Pakistani government but wants it to surrender about 20 people accused by Indian authorities of being linked to militant attacks over the years.

There have also been accusations by some Pakistani media and some lawmakers that the Mumbai attacks were a conspiracy by Hindu extremists to malign Pakistan.

One Indian newspaper quoted a self-styled security expert saying on a Pakistani news television show that the attacks were actually a plan by "Hindu Zionists" and "Western Zionists," including Israel's Mossad.

U.S. Secretary of State Condoleezza Rice, ending her visit to India, was scheduled to arrive in Pakistan Thursday.

Adm. Mike Mullen, chairman of the U.S. Joint Chiefs of Staff who arrived Wednesday, met President Asif Ali Zardari and other military leaders, urging Pakistan to extend cooperation with India in probing the Mumbai attacks, Pakistan's Post reported, quoting sources.

The New York Times reported the Zardari's government is facing tough questions whether it can control the military in face of growing evidence of links between the Mumbai attacks and a Pakistani militant group.

The newspaper quoted a former U.S. Defense Department official as saying U.S. intelligence agencies had determined former officers from Pakistan's Army and its powerful Inter-Services Intelligence agency helped train the Mumbai attackers.

While the United States has not established a direct link to the Pakistani government, The Times report said Rice's visit comes as pressure mounts on the Zardari government to confront the Lashkar-e-Toiba, which Indian and U.S. officials say carried out the Mumbai attacks.