The United States will scrap a plan to reduce the US force in Afghanistan to 5,500 by December, after American commanders appealed to keep more troops on the ground, officials said Monday.

The White House is due to hold meetings in the coming days that will pave the way for a final decision expected to be announced next week, when Afghan President Ashraf Ghani meets US President Barack Obama in Washington.

"There's no final decision but the indications are that the drawdown levels will be revisited," a US defense official told AFP on condition of anonymity.

There are about 10,000 US troops currently in Afghanistan. That number was supposed to drop to about 5,500 by the end of the year before a complete withdrawal by the end of 2016, when President Barack Obama leaves office.

It was unclear how many soldiers would remain in Afghanistan through December under the new plan, though officials estimated the number at roughly 7,000 to 8,000 troops.

US officials, however, said there was no sign that Obama was ready to abandon his frequently stated promise to pull out all American troops by the end of his term.

The rationale for the move was partly due to the election of Ghani, seen by Washington as a promising new figure who, in contrast to his predecessor Hamid Karzai, has signaled a willingness to work constructively with the Americans.

"There's a desire to set him up for success," said the official. "This is a different type of leader."

- Threat from IS jihadists -

Another factor shaping the decision was concern in Kabul and Washington over the potential threat posed by the Islamic State group, after some former Taliban militants swore allegiance to the extremists based in Syria and Iraq.

A militant commander suspected of links to the IS group was killed in a US drone strike last month. And his successor, Hafiz Waheed, was killed by Afghan forces on Sunday, along with other militants in the Sangin district of Helmand province, officials said in Kabul.

Of the 10,000-strong force now in place, about 2,000 are devoted to counterterrorism operations against Al-Qaeda militants and Taliban insurgents and the remainder are training and advising Afghan forces.

US commanders have urged keeping a larger number of troops to support the counterterrorism mission, as well as the training efforts.

Two Republican senators who have demanded a change to the drawdown schedule, John McCain and Lindsey Graham, welcomed signs the White House was ready to revise its plan.

"We are encouraged by media reports that the Obama administration may slow its withdrawal from Afghanistan, potentially allowing a greater US force to continue critical counterterrorism and training missions together with our Afghan partners," the two senators said in a joint statement.

"If these reports are true, this would be a welcome step in the right direction, one supported by our nation's top military commanders given the conditions on the ground."

But the two hawkish lawmakers said Obama should also abandon his vow to pull out the whole force by the end of 2016, saying it would leave a risky "vacuum."

In a visit to Kabul last month, Defense Secretary Ashton Carter raised the possibility of slowing the withdrawal of US troops, saying that it was important to cement gains made in the fight against the Taliban insurgency.