The US government has begun an investigation into whether Pakistan Taliban chief Baitullah Mehsud, who is said to be responsible for the assassination of former prime minister Benazir Bhutto, was killed in a drone attack on Wednesday, senior officials have said in Washington.
DNA tests will be carried out to determine if indeed Mehsud has been killed.
Earlier reports had indicated that one of the wives of Mehsud had been killed in the drone strike in northwestern Pakistan's South Waziristan tribal agency.
US officials on Thursday said they believe "Mehsud himself may have been killed" and that both US and Pakistani teams were investigating the possibility, Wall Street Journal reported on Friday.
"There is reason to believe that reports of his death may be true, but they can't be confirmed," a US official was quoted as saying.
Mehsud was considered one of the most wanted Islamist extremists in Pakistan's western tribal regions, leading a large army of militants that have fought US and Pakistani forces on both sides of the Afghanistan-Pakistan border.
Pakistani officials have accused Mehsud of being behind a number of high-profile terrorist attacks, including the assassination of former prime minister Benazir Bhutto in 2007.
The Central Intelligence Agency, in concert with Pakistan's intelligence service, has conducted a widening campaign against militant leaders inside Pakistan using unmanned Predator drones to conduct air strikes against suspected hideouts.
"Reports of Mehsud's death have circulated in the past, but a US defence official said Pakistani officials appeared to be more certain this time that Mr. Mehsud had been killed," the report said.
"We don't know 100 percent yet," an unnamed US defence official was quoted as saying.
"The Pakistanis seem to be a little more confident this time than they have been in the past."
The US and Pakistan will conduct DNA testing on the body believed to be Mehsud's, using genetic samples taken from members of Mehsud's family, according to the official.
Results could take anywhere from days to weeks.