A Taliban spokesman said Thursday the insurgents were still holding two Western hostages, as officials stayed tight-lipped over the outcome of an apparent prisoner swap announced by Afghan President Ashraf Ghani earlier this week.

Ghani announced on Tuesday that his government would "conditionally" release three high-ranking Taliban insurgents, including Anas Haqqani, brother to the leader of the eponymous Haqqani Network, one of the Taliban's deadliest and most feared factions.

He did not specify the fate of the Western hostages -- an Australian and an American -- but noted that their health had been deteriorating, and that their release would help pave the way for peace negotiations.

Two days later, Taliban spokesman Zabihullah Mujahid confirmed to AFP that no swap had yet taken place.

"The three people have not been handed over to us, and we have not freed our prisoners yet," he said.

The reasons for the delay were not clear. Afghan officials remained tight-lipped Thursday, and the Australian foreign office has said it will not provide a "running commentary" on the process.

The US ambassador had initially welcomed Ghani's statement, but officials have given no further information since.

Waheed Muzhda, who served as an official in the Taliban's 1996-2001 regime, said a bomb blast in Kabul which killed 12 people could have been an effort to sabotage the prisoner swap
Waheed Muzhda, who served as an official in the Taliban's 1996-2001 regime, said a bomb blast in Kabul which killed 12 people could have been an effort to sabotage the prisoner swap AFP / STR

Waheed Muzhda, who served as an official in the Taliban's 1996-2001 regime, said the swap still could happen, but suggested the delay could be an issue of trust.

"The concern is that there will be a tweet by Trump or another American official to say the deal is off, as it happened in the case of peace talks," he told AFP.

Earlier this year, the Taliban and the US were on the verge of a deal that would have seen Washington begin withdrawing troops in return for security guarantees from the insurgents.

Many had hoped the deal would pave the way for direct talks between Kabul and the Taliban, which most analysts agree is the only way to achieve a lasting peace in Afghanistan.

However US President Donald Trump abruptly called off the talks in September, days before the deal was widely expected to have been signed.

Muzhda said the insurgents were insisting that Haqqani and the two other prisoners be delivered in to their custody first -- potentially in Qatar, where they maintain a political office -- before releasing the hostages.

A bomb blast in Kabul on Wednesday which killed 12 people could also have been an effort to sabotage the deal, he said. No group has yet claimed responsibility for the blast.