America has agreed in principle to withdraw 5,000 troops from five military bases in 20 weeks, in a deal with the Taliban to kick start talks with the Afghan government.

The accord which could be announced as early as Wednesday would see US troops begin to pull back from their longest ever conflict, in return for a reduction in Taliban attacks and the start of formal negotiations with Ashraf Ghani's government.

A large blast hit Kabul on Monday evening, close to a heavily fortified compound housing international organisations.The Green Village compound has been struck by several suicide car combs in the past. There was no immediate report of casualties.

The deal brokered over nine rounds of talks in Doha has yet to be signed off by Donald Trump and Mr Ghani was last night consulting with officials after being shown the latest draft of the prospective agreement. Nato allies including Britain will also be briefed on the deal before any announcement. Yet Western officials familiar the talks said final go ahead could be given as early as Wednesday or Thursday.

“Yes, we have reached an agreement in principle,” Zalmay Khalilzad, the top US negotiator, told told Tolo news. “Of course, it is not final until the US president agrees on it. So, at the moment, we are at that stage.”