The controversy over Baitullah Mehsud's death persists
The Pakistani government says it intends to provide conclusive proof that Baitullah Mehsud, leader of the Pakistani Taliban, is dead.
"All the credible intelligence I have from that area does finally confirm [his death]," Interior Minister Rehman Malik told the BBC.
But the government says it hopes to get DNA evidence to back up its claims.
Baitullah Mehsud was reported to have been killed in a US missile strike last week in his remote tribal stronghold.
The BBC's Aleem Maqbool, in Islamabad, says that the Pakistani government is growing increasingly confident that it will soon be able to prove that Baitullah Mehsud was killed in the attack.
In Washington, US National Security Adviser Jim Jones put the level of US certainty that he had been killed "in the 90% category".
But Taliban sources have denied these claims, insisting he is still alive.
BBC's Aleem Maqbool in Islamabad
Pakistan's government says the leader of the Taliban is dead and its commanders in disarray. The militants insist that their chief is alive and the Taliban united.
Neither Pakistani officials nor the Taliban have yet managed to provide hard evidence to back up their claims. With each passing day, that is only driving more and more speculation.
Could the government be bluffing to sow the seeds of suspicion within Taliban ranks, or to flush out militant leaders to prove that they are still alive? Is the official intelligence simply wrong? Have the militants already buried their leader, and are they now trying to protect their tribal coalition from panic or even disintegration?
Through the media, each side is heaping pressure on the other.
Mr Malik said the government was working to obtain DNA evidence to establish that the Taliban commander had been killed.
The government had previously said that it would be extremely difficult to get DNA proof of his death.
But Mr Malik told the BBC's Urdu service that they did have DNA from Mr Mehsud's brother, who was killed a few months ago.
However, correspondents say that getting hold of Baitullah Mehsud's body in the remote and hostile terrain of South Waziristan could prove to be a stumbling block.
The Pakistani interior minister has challenged the Taliban to prove its leaders are still alive - something the Taliban commanders dismissed as a ploy to flush them out into the open
On Sunday a key aide of the militant commander said that Baitullah Mehsud was gravely ill and had not been injured in the missile attack.
It is thought that in making the statement the Taliban are preparing the ground for an announcement that Pakistan's most wanted man is in fact dead, correspondents say.
But the fate of the entire leadership of the Pakistani Taliban is subject to intense speculation, after days of conflicting reports about its fate.
Mr Malik has said that he believes the next tier of Taliban leadership is in turmoil, after it was reported that up to two potential successors were killed in a gun battle.
Senior Taliban commander Hakimullah Mehsud - who contacted the BBC on Saturday to say his chief was alive and well - was one of those reported to have been killed in the alleged fight over the succession.
However he got in touch with the BBC on Monday to say that he was in fact alive.
Officials have constantly emphasised the difficulty of getting accurate information from the remote region.
The interior minister said the government was determined to pursue the remaining Taliban leaders encamped in the area.
"We are not going to stop our law enforcement action until the last Talib is flushed out. They have no option except to get killed or surrender," he said.
But Mr Malik expressed concern about the possibility of al-Qaeda moving in to fill any void that might have been left by the death of senior Taliban commanders.
"They are trying to find someone to install him as chief terrorist in area," he said.