WASHINGTON, Nov 20: US Secretary of State John Kerry has not accepted Afghan President Hamid Karzai’s invitation to attend the grand assembly of Afghan tribal elders which begins in Kabul on Thursday, the State Department said.

A statement issued by Mr Kerry’s office said that the secretary telephoned the Afghan president on Tuesday morning and both leaders reiterated the importance of moving towards a bilateral security agreement.

“President Karzai invited the secretary to attend the Loya Jirga and Secretary Kerry thanked him for the invitation, but conveyed that it would not be possible for him to attend this week,” the statement said.

More than 2,500 public figures from across Afghanistan will attend the four-day Loya Jirga President Hamid Karzai inaugurates on Thursday. All 34 state governors – along with lawmakers, tribal leaders, religious scholars, academics, lawyers, civil society activists and representatives of Afghan refugees in Pakistan and Iran – have been invited to the gathering.

The Loya Jirga will decide whether the United States can keep its troops in Afghanistan after 2014 and on what conditions. Although not legally binding on the government, the decisions taken at the Jirga will play a key role in finalising a bilateral security agreement that the United States and Afghanistan are currently negotiating.

The US media reported on Wednesday that when President Karzai spoke to Mr Kerry on Tuesday, the two leaders reached a tentative agreement on the critical security pact.They also agreed that President Obama would write a letter to the Afghan people acknowledging mistakes during the “war on terror”.

The State Department’s statement on the Karzai-Kerry meeting also addressed the Afghan demand for an apology letter, albeit indirectly.

According to the State Department, President Karzai asked for reassurances that he could communicate to the Loya Jirga regarding the nature of a bilateral security relationship going forward and addressing past issues such as civilian casualties.

Secretary Kerry indicated that “we want to continue working together to find a path forward, and that we will consider his request for reassurances, including the option of a letter from the administration stating our position”.

Secretary Kerry also conveyed that it was important to move forward given the need for certainty and for the United States and its partners to plan ahead.

A spokesman for the Afghan president, while talking to The New York Times, gave a different version of this conversation. He claimed that Secretary Kerry proposed the letter during the telephone call.

President Karzai wanted President Obama to sign it, and Mr Kerry reportedly agreed.

“The letter apparently helped them reach a tentative deal authorising US raids on Afghan homes in certain circumstances, which had been an area of disagreement,” NYT reported.

White House Press Secretary Jay Carney, when asked by Fox News, would not confirm or deny the letter.