By Steve Holland

WASHINGTON (Reuters) -President Joe Biden on Thursday will offer his most extensive comments to date about the U.S. withdrawal from Afghanistan, a pullout that is raising concerns about a civil war there and drawing Republican criticism.

A senior administration official said Biden will provide an update on U.S. plans to move thousands of Afghan interpreters out of the country by the end of August.

The Democratic president, scheduled to speak at 1:45 p.m. (1745 GMT), has been under pressure from critics to give a more expansive explanation for his decision to withdraw.

The United States last weekend abandoned Bagram air base, the longtime staging ground for U.S. military operations in the country, effectively ending America’s longest war. The Pentagon says the withdrawal of U.S. forces is 90% complete.

Washington agreed to withdraw in a deal negotiated last year under Biden’s Republican predecessor, Donald Trump. Biden overruled military leaders who wanted to keep a larger presence to assist Afghan security forces and prevent Afghanistan from becoming a staging ground for extremist groups.

Instead, the United States plans to leave 650 troops in Afghanistan to provide security for the U.S. Embassy.

Biden’s order in April to pull out U.S. forces by Sept. 11 after 20 years of conflict has coincided with major gains by the Islamist militant Taliban movement against overwhelmed Afghan forces after peace talks sputtered.

The commander of U.S. troops in Afghanistan, General Austin Miller, warned last week that the country may be headed toward a civil war.

The U.S. intelligence community believes the Afghan military is weak and that the Kabul government’s prospects for survival in the short term are not good, U.S. government sources familiar with official assessments said.

Biden’s administration is also grappling with its plan for expedited visas for Afghan people most at risk of being attacked by the Taliban, including translators who worked with foreign forces. Rights groups are pushing to add up to 2,000 vulnerable women to the list, and Biden is expected to mention women’s rights in his remarks.

The senior administration official said the United States plans to move the interpreters to temporary locations while awaiting valid U.S. visas. Locations are still being worked out. Guam, Qatar and the United Arab Emirates are possible locations.

White House spokeswoman Jen Psaki said Biden would meet his national security team ahead of his remarks on Thursday “to receive a periodic update on the progress of our military drawdown from Afghanistan.”

“The president will make comments on our continued drawdown efforts and ongoing security and humanitarian assistance to the ANDSF and the Afghan people,” she said, referring to the Afghan National Defense and Security Forces.

Some Republicans are criticizing Biden for the pullout, although Trump had also sought to end American involvement in the war.

Biden met Afghan leaders at the White House on June 25 and said U.S. support for Afghanistan would continue despite the pullout.

“Afghans are going to have to decide their future, what they want,” he said at the time.

(Reporting by Steve Holland; Additional reporting by Mark Hosenball; Editing by Ross Colvin and Alistair Bell)