"Her confirmation will thus undercut the work of countless diplomats, military service members, and intelligence professionals who continue to engage with their foreign counterparts on why the United States believes that torture and other forms of abuse are not only morally wrong but strategically shortsighted and legally impermissible," the letter said.
The ambassadors said that if evidence proves Haspel participated in torture, detainee abuse, or destroying evidence related to those activities, her nomination should be rejected.
READ MORE: Alleged 9/11 Plotter Vows to Testify on Haspel's Role in CIA Tortures — Reports
The diplomats said Haspel represents problematic choices made by American leaders in the wake of the September 11, 2001 attacks, according to the letter.
US media reported that Haspel has told multiple US Senators in private meetings that she would never allow the CIA restart an interrogation and detention program. The Senate confirmation hearing for Haspel will be held on Wednesday.