Pakistan is under "tremendous pressure" from the US to extradite Lashker-e-Taiba operations commander Zakiur Rahman Lakhvi, the alleged mastermind of the Mumbai terror attacks, to India, a media report said on Wednesday.
The Americans are believed to have given Pakistan a taped conversation Lakhvi allegedly had with gunmen involved in attacks on Mumbai on November 26.
American audio experts had checked the tape and concluded it was genuine and that the speaker was Lakhvi, the Dawn newspaper quoted US and diplomatic sources as saying.
Though Indian officials had been saying for some time that Lakhvi should be handed over to India, US officials had not taken a clear stand on this issue until this week. Lakhvi's conversation with the gunmen appeared to have changed their minds, the report said.
Diplomatic sources in Washington told the newspaper that the Americans were now "urging Pakistan to hand over Lakhvi to New Delhi".
Lakhvi was detained along with over 20 other LeT and Jamaat-ud-Dawah activists during a crackdown by Pakistani security forces near Muzaffarabad, the capital of Pakistanoccupied Kashmir, on December 7.
Prime Minister Yousuf Raza Gilani has confirmed that Lakhvi was among the militants detained but his current whereabouts are not known.
Pakistan has so far said it will not hand over to India any of its nationals found to be linked to the Mumbai attacks. It has also said that such individuals will be tried under Pakistani laws.
Reports in the US media have said that Lakhvi came from the same area in Pakistan as Ajmal Amir Iman alias Ajmal Kasab, the lone gunman arrested in Mumbai out of the 10 terrorists who killed over 180 people.
The Dawn reported that officials in Islamabad appeared reluctant to accept the intercepts of Lakhvi's conversation provided to them by American and British intelligence agencies as authentic.
The intercepts include Lakhvi's cellphone conversations with gunmen holed up inside Mumbai's Taj Hotel during the 60-hour siege.
Officials in Pakistan said Kasab's confession and other evidence were inadmissible in court. They said that since the confessions had been "obtained under severe pressure" by the Indians, this could not be admissible in any judicial process.
They have insisted that the information provided will not stand scrutiny in court, the report said.
There is also a "serious difference of opinion between Islamabad and the Pakistan embassy in Washington over the issue", the report added. While Islamabad is "reluctant to accept the evidence as authentic, the embassy insisted that it is authentic and that the Pakistani authorities now needed to take steps to satisfy the international community", it said.
It was not yet clear if the US recorded the conversations between Lakhvi and the terrorists in Mumbai using their own surveillance methods or received the tape from India, which has accused Lakhvi of masterminding the attacks.
On December 4, Indian officials told journalists in Delhi that they believed Lakhvi and LeT operative Yusuf Muzammil had masterminded the Mumbai attacks.
Officials in New Delhi and Washington have said they would not be satisfied unless Islamabad followed up by prosecuting those arrested and taking further action against other militant groups linked to attacks on Indian soil.