The US and the Taliban, at war since 2001, are on the verge of agreeing a landmark withdrawal deal to be signed in Qatar, an insurgent source told AFP Tuesday.

An Afghan official suggested the deal could be inked on February 29 in Doha, depending on the success of a violence reduction period agreed last week after long negotiations between Washington and the jihadists.

The US wants to reduce its military presence in Afghanistan, which currently numbers between 12,000 and 13,000, with President Donald Trump keen to make good on a promise to bring troops home after 18 years of war.

"All the arrangements have been finalised and the leadership council has given a go ahead signal to the Taliban negotiating team," a Taliban source in Pakistan said.

There have been previous false dawns in Afghanistan, with a deal all but complete in September before Trump nixed it at the last moment amid continued Taliban violence. The Taliban source said the jihadists would meet the US negotiators in Doha on Sunday to agree a date and location for the signing ceremony.

Both sides were close to agreeing to hold the ceremony during the last week of February, he added. "Even last time, we were committed to sign the deal, but it was US President Trump's decision to backtrack from what both the teams had agreed in Doha," the Taliban source said. "(The signing) is going to happen this time."

The Afghan official suggested the ceremony would "take place in Doha if the violence reduction period goes smoothly".

Masoud Andarabi, Afghanistan's acting interior minister, said at a workshop in Kabul on Tuesday that the violence reduction period "begins in the next five days". The Kabul government did not comment on his announcement. Afghan President Ashraf Ghani has said the Taliban's sincerity in entering the violence reduction agreement was unproven. "That's the billion dollar question," Ghani said at the Munich Security Conference on Saturday.

But, he added, "you're not going to find an answer to this question unless you engage in the peace process."

Ghani was named on Tuesday the winner of Afghanistan's presidential polls held in September 2019. His rival Abdullah Abdullah contested the final results, vowing he would form his own parallel government.