The three met in Poland's capital Warsaw to discuss a potential new deal to secure the release of Israeli hostages held in Gaza in exchange for a potential release of Palestinians in Israeli prisons and a "humanitarian pause" in Gaza's war.

"The talks were positive with negotiators exploring and discussing different proposals in an attempt to progress on negotiations," the source told Reuters. "An agreement is not expected imminently however."

In a statement on Tuesday, Israeli Prime Minister Benjamin Netanyahu said he had "sent the head of the Mossad to Europe twice to promote a process for the release of our hostages", without giving details of what was discussed.

"I will spare no effort on the subject and the demand is to bring everyone (home)," Netanyahu said

There was no immediate comment from the CIA.

The talks between Qatari Prime Minister Mohammed bin Abdulrahman Al Thani, who also serves as the Gulf state's foreign minister, Mossad Director David Barnea and CIA Director Bill Burns followed a meeting of the three in Europe last week.

Qatar has said it is working to repair a humanitarian truce deal that collapsed after a week on Dec. 1, and pushing for a comprehensive end to the more than two-month-old Israel-Hamas war that has caused a humanitarian disaster in Gaza.

Qatar and Egypt were mediators between Israel and Hamas in the late November truce during which Hamas released 110 women, children and foreigners it was holding in exchange for 240 Palestinian women and teenagers freed from Israeli jails.

(Reporting by Alexander Cornwell; additional reporting by Emily Rose in Jerusalem and Jonathan Landay in Washington; editing by Hugh Lawson and Mark Heinrich)