Israeli negotiators attending ceasefire and hostage release talks in Doha have expressed “cautious optimism,” even as some gaps between both sides persist, a source familiar with the matter told CNN.

Spy agency director David Barnea's presence means high-level Israeli officials who would need to sign off on any agreement are now involved Israeli Prime Minister Benjamin Netanyahu is sending the director of the Mossad foreign intelligence agency to ceasefire negotiations in Qatar,

It wasn't immediately clear on Saturday when David Barnea would travel to Qatar’s capital for the latest round of indirect talks.