Image caption Hamid Karzai had urged delegates at the Loya Jirga to support the pact

The Afghan president has refused to back down on his decision not to sign a key security deal in a meeting with the US national security adviser.

The pact allows thousands of US troops to remain in Afghanistan after 2014.

US envoy Susan Rice told President Hamid Karzai his proposal to delay the signing until after next year's elections was "not viable".

Their meeting came a day after elders at a grand assembly in Kabul called for the deal to be signed this year.

Further assurances

"President Karzai outlined new conditions for signing the agreement and indicated he is not prepared to sign the bilateral security agreement (BSA) promptly," the White House said in statement.

Mr Karzai's office said he used the meeting with the US envoy to ask for further assurances from the US that its forces will not raid Afghan homes, and that it will help start stalled peace talks with the Taliban.

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He repeated his demand that the US commits to holding free and transparent elections on 5 April.

Also among the terms of his conditions was the return of Afghan citizens held in Guantanamo Bay, according to reports.

Washington insists the deal - which has taken months to negotiate - must be signed before the end of this year in order to secure plans for how many US troops will remain in Afghanistan beyond 2014.

Ms Rice said in Monday's meeting that waiting to sign the deal "would not provide the United States and Nato allies the clarity necessary to plan for a potential post-2014 military presence".

Nor would it give Afghans certainty, she said.

The deal under discussion may see 15,000 foreign troops remain after 2014, although the US says it has not yet taken a decision on any presence.

The soldiers who stay beyond 2014, when most foreign combat forces leave, would primarily train and mentor Afghan forces. Some special forces would stay to conduct "counter-terror operations".

Member of Afghanistan's grand assembly of elders, or Loya Jirga, approved the deal on Sunday.

"The Loya Jirga requests the president to sign the agreement before the end of 2013," a declaration reached at the end of the meeting said.

Opening the assembly on Thursday, Mr Karzai urged delegates to support the pact, but said he would not sign it until after the election scheduled for April 2014.

The BSA also has to be approved by the Afghan parliament.