On Monday, the Taliban launched a massive attack in Kabul. (File photo)

The Afghan government expressed doubts Wednesday about a prospective deal between the US and the Taliban, saying officials need more information about the risks it poses.

US special envoy Zalmay Khalilzad was in Kabul this week, when he shared with Afghan officials an agreement "in principle" that Washington has forged with the Taliban and would lead to a pull-out of American troops.

The prospect of a US-Taliban deal has caused much concern among many Afghans, who feel sidelined from the process, worry the hardline Islamists will return to power, and see a beaten America selling out their interests in a bid to escape Afghanistan after 18 years of gruelling war.

Sediq Sediqqi, Afghan President Ashraf Ghani's spokesman, said that while the Kabul administration supports any progress in an eventual peace process, it wants to prevent any negative consequences.

Kabul is "concerned, therefore we seek clarification about this document so that we can carefully analyse the risks and potential negative consequences, and prevent any danger it may cause," Sediqqi said on Twitter.

The statement is Kabul's first such reaction to the prospective deal, which Khalilzad presented on Monday.

Ghani and his government have until now been largely sidelined in negotiations between the US and the Taliban, who see the Afghan president as illegitimate and have insisted on dealing first with the Americans.

Kabul's concerns build on a position expressed Tuesday by former US ambassadors to Afghanistan, who warned in a joint statement against a major troop withdrawal without a comprehensive peace accord.

"A major withdrawal of US forces should follow, not come in advance, of (a) real peace agreement," the former envoys wrote.

Five US bases

According to parts of the deal made public so far, the Pentagon would pull thousands of its 13,000 or so troops from five bases across Afghanistan by early next year, provided the Taliban hew to their security pledges.

The insurgents have said they will renounce Al-Qaeda, fight the ISIS group and stop terrorists using Afghanistan as a safe haven.

Ultimately, though, Kabul has no say on whether the US and the Taliban make a deal, and can only hope the insurgents honour a pledge to sit down with the Afghan government to build a separate accord.

Afghans have been on tenterhooks for weeks while the US and the Taliban flesh out what are thought to be the final details of their deal.

US President Donald Trump was due to look at the proposed pact this week. If he and Taliban leaders approve, it could be signed and announced any day.

But even as negotiations for an accord have entered an apparent end phase, violence has surged across Afghanistan.

On Monday, the Taliban launched a massive attack in Kabul, where they targeted a fortified compound used by foreign aid groups and agencies.

At least 16 people were killed, with more than 100 wounded.

On Saturday, the Taliban attempted to seize the provincial capital of Kunduz in the north, and on Sunday, they launched an operation in the city of Pul-e Khumri, the capital of neighbouring Baghlan province.