The United States said on Friday it could not confirm it had killed Pakistani Taliban leader Baitullah Mehsud in a drone strike, but said Pakistanis would be safer with such a "murderous thug" dead.
Mehsud was believed killed when a US drone fired two missiles into a family home in the Laddah area of South Waziristan on Wednesday.
Security officials in Islamabad and Washington were trying to verify his death.
"The United States cannot confirm that has been killed in a drone attack, White House spokesman Robert Gibbs said, but added "there seems to be a growing consensus among credible observers that he is indeed dead."
"Baitullah Mehsud is somebody who has well earned his label as a murderous thug," Gibbs said, adding that President Barack Obama was being offered regular updates on the situation.
"He has planned and helped carry out some of the most heinous acts of terrorism and violence that we have seen in Pakistan.
"He has killed scores of innocent men, women and children and is supposed to have plotted the assassination of Benazir Bhutto.
"If he is dead, without a doubt, the people of Pakistan will be safer as a result.
Gibbs said that the United States was working closely with the government of Pakistan to prevent the Taliban, Al-Qaeda and other affiliated terrorist organizations from killing innocent people."
The death of the notorious commander could deal a heavy blow to the sizeable Taliban movement commanded by Mehsud, who had a five-million-dollar US bounty placed on his head after Washington branded him "a key Al-Qaeda facilitator".
Senior officials in Pakistan's powerful security establishment who supervise operations in Mehsud's Waziristan stronghold said the warlord was dead, but the Islamabad government said it was seeking verification.