US Defense Secretary Chuck Hagel called Egyptian army chief General Abdel Fattah Al-Sisi on Tuesday and the two also spoke last week, the Pentagon said on Wednesday, declining to offer details of the conversations.

Asked why the Pentagon had previously declined to disclose the calls, spokesman George Little told reporters: "I think you can understand the sensitivities of this situation and that's in essence the bottom line."

"We made a decision to acknowledge the phone call and that's where we are."