Afghan President Hamid Karzai on Saturday called on the Taliban and their allies to join an assembly on a security pact that could allow some US troops to stay in the country after 2014.

Around 2,500 tribal elders and civil leaders are expected to take part in an assembly known as a "loya jirga" next Thursday, to decide whether to accept the draft Bilateral Security Agreement between Afghanistan and the US.

"We invite them, please come to this national jirga of Afghanistan, raise your voice, raise your objection... and share your views," he told a news conference in Kabul.

The draft pact was hammered out in Kabul last month during a visit by US Secretary of State John Kerry. But he left without a final deal as Afghan President Hamid Karzai said only a jirga had the authority to decide the contentious issues.

These include a US demand to retain legal jurisdiction over its troops in Afghanistan, which would give them immunity from Afghan law. The request emerged as the main sticking point after Kerry's visit.

The Taliban, whose government was toppled by a US-led invasion in 2001, has rejected the jirga and warned members its that they would be punished as "traitors" if they endorsed the deal.

Hezb-e-Islami, a Taliban affiliate has also refused to send members to jirga calling it "legalising the US occupation".

"This security agreement has supporters who support it without reasoning and also has oppositions who oppose it without reasoning," Karzai said.

If the agreement is passed by both loya jirga and parliament, between 5,000 and 10,000 US troops would stay in Afghanistan to help fight Al-Qaeda remnants and train the national army.

Washington had been pushing for the agreement to be signed by the end of October to allow the US-led NATO coalition to plan the withdrawal of its 75,000 combat troops by December 2014.

The collapse of a similar security agreement with Iraq in 2011 led to the US pulling all its troops out of the country, which is currently suffering its worst sectarian violence since 2008.