"There are approximately 20,000 Afghans who have applied," Press Secretary Jen Psaki told reporters.

Psaki said those are all former translators for the military or other entities, whom the Taliban have targeted.

However, the United States will also consider applications by the families of the interpreters, she said, without specifying how many family members would be allowed.

According to some estimates, the number of people eligible to leave would total around 100,000.

Officials say evacuations will start this month.

The interpreters being readied for evacuation are those who have already filed applications under the State Department program of Special Immigrant Visas (SIV) for Iraqi and Afghan translators and interpreters.

Psaki said those who have completed security vetting could then be temporarily housed at a US military base.

Those still needing to go through the vetting process, will first be sent either to a US base abroad or a third country "where they will be safely housed until their visa processing is going on," Psaki added.

Meanwhile, two senior senators urged President Joe Biden to speed up the evacuations and make sure Afghans who aided US intelligence services are also included.

"For two decades, thousands of Afghans have risked their lives to work with intelligence professionals from the United States and other NATO countries to fight Al Qaeda, the Haqqani Network, ISIS and other terrorist groups," wrote Mark Warner and Marco Rubio, the chair and vice chair of the Senate Intelligence Committee.

"Their efforts contributed to the decimation of Al Qaeda and its ability to attack the US homeland," they said in a letter to Biden.

They urged Biden to expedite the SIV program but also consider evacuating the Afghans to third countries and giving them priority to immigrate under US refugee programs.

They questioned whether, given the rapid pullout from Afghanistan by US forces, there is enough capacity to evacuate Afghans who helped Americans.

"Abandoning these individuals, who have provided essential support to our intelligence community in Afghanistan, would send a damaging message to our allies and potential partners about the United States' reliability and trustworthiness," they wrote.

"It would also be a stain on our national conscience."