WASHINGTON: A longtime CIA clandestine operations official reportedly involved in its much-criticized "black site" interrogations after the 9/11 attacks was named number two at the US spy agency Thursday.

Gina Haspel, the first female head of the Central Intelligence Agency's clandestine service, was named deputy director of the overall organization under its new director, Mike Pompeo.

A veteran of the agency's undercover spy operations, Haspel joined the Central Intelligence Agency in 1985 and served in posts around the world, including a stint in the US embassy in London in the late 2000s.

She was named acting head of the CIA National Clandestine Service in 2013, but was replaced within weeks - reportedly due to concerns over her senior role in the post-9/11 interrogation operations, which involved methods widely deemed to be torture, such as waterboarding.

The Washington Post reported that year that she "had run a secret prison in Thailand where two detainees were subjected to waterboarding and other harsh techniques."

That was where Al-Qaeda suspects Abu Zubaydah and Abd al-Rahim al-Nashiri were interrogated and repeatedly waterboarded.

The Post said Haspel was also involved in the 2005 destruction of the CIA's videotapes of its "enhanced interrogation" sessions of several detainees in Thailand. Lawyers for Al-Qaeda detainees had wanted the tapes for evidence in court cases.

Pompeo praised Haspel in a statement, saying "Gina is an exemplary intelligence officer and a devoted patriot who brings more than 30 years of agency experience to the job.

"She is also a proven leader with an uncanny ability to get things done and to inspire those around her," he said.

Three former CIA chiefs and other top intelligence officials including James Clapper, former Director of National Intelligence, also voiced strong support for her.

Haspel's appointment comes amid concerns that the US intelligence services under President Donald Trump could return to the harsh and possibly outlawed tactics of secret arrests, renditions and torture.

Trump has said he thinks torture works but that he will defer to Defense Secretary James Mattis on the issue; Mattis has said he is opposed to torture.

In his confirmation hearings to be CIA director, Pompeo said he would "absolutely not" resume the use of banned interrogation tactics.

In a subsequent statement, CIA spokesman Jonathan Liu would not comment on Haspel's links to its interrogation program.

"As has been well-documented, the former detention and interrogation program was authorized by President [George W] Bush six days after 9/11, reviewed and determined to be lawful by the Justice Department, and implemented by the CIA. Eight years ago in January 2009, an Executive Order ended the program," he said.

Former CIA acting director Michael Morrell said Haspel had done nothing wrong or illegal in her work at the CIA.

"Some of the assignments that she took on have later come under political fire, but in each case she was following the lawful orders of the president," he wrote on the website The Cipher Brief.

"And, in each case, she carried out her responsibilities within the bounds of the law and with excellent judgment," he said.

He acknowledged that she drafted a cable instructing other operatives to destroy the interrogation tapes.

"She did so at the request of her direct supervisor and believing that it was lawful to do so. I personally led an accountability exercise that cleared Haspel of any wrongdoing in the case," Morrell said.

But late Thursday two Democratic senators expressed their concerns over Haspel's appointment in a letter to President Trump.

"Her background makes her unsuitable for the position," said senators Ron Wyden and Martin Heinrich.

They said their specific reasons were contained in a separate classified letter.

Senator Mark Warner, the senior Democrat on the Senate Intelligence Committee, said he wanted to hear from Haspel herself on the issue.

"I appreciate Ms Haspel's many years of service at the CIA, yet I want some reassurance from her that she intends to comply with both the spirit and the letter of the law," he said in a statement.