The United States would withdraw almost 5,000 troops from Afghanistan and close five bases within 135 days under a draft peace accord agreed with the Taliban, the chief U.S. negotiator, Zalmay Khalilzad, said on Monday.

The deal, reached after months of negotiations with representatives from the insurgent movement, must still be approved by U.S. President Donald Trump before it can be signed, Khalilzad said in an interview with Tolo News television.

"In principle, we have got there," he said. "The document is closed."

In exchange for the phased withdrawal, the Taliban would commit not to allow Afghanistan to be used by militant groups such as al Qaeda or ISIL as a base for attacks on the United States and its allies.

The distance that must still be covered before peace is achieved was underlined, however, by a large explosion that rocked the Afghan capital, Kabul, even as Khalilzad's interview was being aired, shaking buildings several kilometers away.

Khalilzad, a veteran Afghan-American diplomat, said the aim of the deal was to end the war and that it would lead to a reduction in violence, but there was no formal ceasefire agreement. It would be up to negotiations among Afghans themselves to agree a settlement, he said.

He declined to say how long the rest of the roughly 14,000 U.S. troops would remain in Afghanistan after the first stage of the withdrawal, although Taliban officials previously insisted that all foreign forces must leave.

Afghan President Ashraf Ghani has been briefed on a draft of the accord and will look at details of the deal before giving an opinion, his spokesman said on Monday.

Khalilzad said "intra-Afghan" talks, which might be held in Norway, would aim to reach a broader political settlement and end the fighting between the Taliban and the Western-backed government in Kabul.

Details of any future negotiations remain unclear, with the Taliban so far refusing to deal directly with the government, which it considers an illegitimate "puppet" government.

Direct negotiation

Ghani met Khalilzad and will "study and assess" details of the draft, spokesman Sediq Sediqqi told reporters earlier on Monday. "But for us, a meaningful peace or a path to a meaningful peace is the end of violence and direct negotiation with the Taliban," he said.

Many Afghan government officials have resented the exclusion of the government from the U.S.-Taliban talks, an issue that was underlined when Ghani was not allowed to keep a text of the draft agreement after it was shown to him.

Several details of the agreement remain to be clarified, including the status to be accorded to the Taliban, which the draft recognizes under their preferred title as the Islamic Emirate of Afghanistan. Some Afghan officials object to that as they see it according the insurgents an equivalent status to the country's internationally recognized government.

At the same time, presidential elections, scheduled for Sept. 28 in which Ghani is seeking reelection to a second five-year term, were not covered in the agreement, Khalilzad said. The Taliban have consistently rejected the elections.

Khalilzad, who has completed nine rounds of talks with Taliban representatives, is scheduled to hold meetings with a number of Afghan leaders in Kabul this week to build a consensus before the deal is signed.

The peace talks have taken place against a backdrop of relentless violence, even before Monday's blast in Kabul, with the Taliban mounting two large-scale attacks on the major northern cities of Kunduz and Pul-e Khumri at the weekend.

Afghan security forces pushed back Taliban fighters from both cities, but a suicide bomber detonated his explosives on Monday in Kunduz, killing at least six policemen and wounding 15, officials and the Taliban said.

Trump has made little secret of his desire to bring the 14,000 U.S. troops home from Afghanistan, where American troops have been deployed since a U.S.-led campaign overthrew the Taliban in 2001.

But there are concerns among Afghan officials and U.S. national security aides about a U.S. withdrawal, with fears Afghanistan could be plunged into a new civil war that could herald a return of Taliban rule and allow international militants, including Islamic State, to find a refuge.

Read more: U.S., Taliban close to peace deal, says U.S. official