US says Gaza ceasefire still 'close' despite tensions

Israel and Hamas are still close to a ceasefire deal, the White House insisted, despite growing fears of a regional war following the assassination of a key Hamas leader.

Washington is still engaged in "intense diplomacy" to prevent further escalation after Iran threatened revenge for the killing of Hamas political leader Ismail Haniyeh in Tehran.

Hamas has named Yahya Sinwar -- the alleged mastermind of the October 7 attack on Israel -- as its new leader, sparking fears the torturous negotiations have become even more difficult.

"We are as close as we think we have ever been" to a deal for a Gaza ceasefire and the release of hostages held by Hamas, National Security Council spokesman John Kirby told reporters Wednesday.

U.S. officials have said on several occasions in recent weeks that a deal is close, while urging both Israel and Hamas to accept the current proposal which would lead to an initial six-week truce.

On Tuesday the White House said negotiations had "reached a final stage," in a readout of calls between President Joe Biden and the leaders of Qatar and Egypt, but did not elaborate.

The United States is now working to prevent an all-out war in the region, and has moved planes and warships into the area to help defend Israel if necessary.

"We're involved in some pretty intense diplomacy here across the region," Kirby said.

He added that he was "not going to talk about intelligence assessments" of when, or whether, Iran and its Lebanese ally Hezbollah might attack.

U.S. Secretary of State Antony Blinken said on Tuesday that he had told both Iran and U.S. ally Israel to avoid escalating conflict.