As many as 1,500 American citizens may still need to be evacuated from Afghanistan, U.S. Secretary of State Antony Blinken said on Wednesday, adding that the Taliban had pledged to allow departures after foreign troops leave. 

"We are aggressively reaching out to them multiple times a day through multiple channels of communication... to determine whether they still want to leave," Blinken told reporters at a news conference. 

He also said that Washington has so far evacuated 4,500 U.S. citizens and their families, as President Joe Biden's deadline of August 31 to withdraw U.S. troops is just days away.

He said the United States would work to ensure Americans and Afghan partners leave Afghanistan beyond August 31. 

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Biden confirmed on Tuesday that his administration aimed at completing evacuation by the deadline, and also asked for contingency plans to adjust the timeline if necessary. 

"We will use every diplomatic, economic assistance tool at our disposal, working hand-in-hand with the international community, first and foremost to ensure that those who want to leave Afghanistan after the 31st are able to do so," said Blinken when asked about steps to assure "high-risk Afghans" would not be left behind after the U.S. troops withdrawal. 

The top U.S. diplomat said the Afghan Taliban had made "public and private commitments to provide and permit safe passage for Americans, for third-country nationals and Afghans at risk going forward past August 31." 

Taliban spokesperson Zabihullah Mujahid said on Tuesday that they want the U.S. to change its policy of encouraging Afghans to leave.

The United States has been scrambling to evacuate Americans and its Afghan partners from the country since the Taliban retook the capital Kabul on August 15. 

(With input from agencies)

(Cover: U.S. Secretary of State Antony Blinken pauses while speaking about Afghanistan during a media briefing at the State Department in Washington, D.C., U.S., August 25, 2021. /CFP)