The United States and 17 other countries demanded Hamas release all the hostages it holds in Gaza as Biden administration officials tried to ratchet up global pressure on the militant group, which the White House blames for blocking a cease-fire deal that would see the release of hostages.

“We call for the immediate release of all hostages held by Hamas in Gaza for over 200 days. They include our own citizens,” the joint statement said. “The fate of the hostages and the civilian population in Gaza, who are protected under international law, is of international concern.” 

The letter was signed by the leaders of the U.S., Argentina, Austria, Brazil, Bulgaria, Canada, Colombia, Denmark, France, Germany, Hungary, Poland, Portugal, Romania, Serbia, Spain, Thailand and the United Kingdom.

“We emphasize that the deal on the table to release the hostages would bring an immediate and prolonged ceasefire in Gaza, that would facilitate a surge of additional necessary humanitarian assistance to be delivered throughout Gaza, and lead to the credible end of hostilities,” the statement said. “Gazans would be able to return to their homes and their lands with preparations beforehand to ensure shelter and humanitarian provisions.”

A senior administration official told reporters in a telephone briefing that the joint statement from such a long list of governments was “quite extraordinary” and that an earlier attempt to organize a similar appeal was not possible given “some of the disagreements.”

The proposal on the table that has been discussed in recent weeks calls for the release of dozens of sick, elderly and wounded hostages in Gaza in return for a six-week cease-fire that could be extended. Qatar, Egypt and the U.S. have acted as intermediaries in the negotiations.

The proposal would open the way for more humanitarian aid to flow to Gaza and for Palestinian civilians to return to their homes in northern Gaza, according to the senior administration official. The Israelis have accepted the terms, but the Hamas leader in Gaza, Yahya Sinwar, so far has rejected the proposal, even though it meets most of Hamas’ demands, the official said.

Negotiations with Hamas political leaders based in Qatar have made some progress, the official said, but Sinwar is “the ultimate decision maker” and he has vetoed some proposals.

As “Gazans are suffering and the question … for him [is], will he agree to release this vulnerable category of hostages to secure cease-fire and relief for Gazans? And the answer that comes back from Sinwar personally, is ‘no,’” said the official.

Asked about Sinwar’s whereabouts and whether he has ventured out of the Hamas tunnel network underneath Gaza, the official said: “I think justice will come for Sinwar. I’m not going to talk about kind of where he is or anything else.”

Israel has vowed to kill Sinwar in the wake of the Oct. 7 terror attack on Israel by Hamas, which claimed the lives of some 1,200 people, mostly civilians.

Hamas says Israel is to blame for a lack of agreement in the hostage-cease-fire talks and has demanded a permanent cease-fire.

Asked about the prospects for an agreement, the administration official said, “You know, we do see some indications that there might be an avenue here, but I’m just … I’m not totally confident.”

Thursday’s joint statement was issued after President Joe Biden met in the Oval Office on Wednesday with former hostage Abigail Edan, a 4-year-old American girl who was captured after Hamas militants killed her parents.

Biden’s meeting with Edan and her family, including her great aunt and uncle, lasted for “over an hour,” the administration official said.

Edan “crawled through the door in the resolute desk,” the official said, referring to the famous photo of President John F. Kennedy’s son doing the same. Edan played on a swing set and a playground on the south lawn of the White House, the official added.

Administration officials also are assessing a new video of an American hostage, Hersh Goldberg-Polin, that was released by Hamas on Tuesday, the official said.