Israel has stepped up its attacks in the Gaza strip, killing at least 13 more people and destroying a residential tower in a siege that has entered its sixth month.

Deaths also continue across the besieged strip from malnutrition and starvation.

Meanwhile, Efforts to secure a deal on a ceasefire between Israel and Hamas in Gaza are ongoing, Israel’s intelligence agency Mossad said on Saturday, despite dimming hopes for a truce during the Muslim holy month of Ramadan.

Mossad chief David Barnea met on Friday with his U.S. counterpart, CIA Director William Burns, to promote a deal that would see hostages released, Mossad said in a statement. U.S. President Joe Biden said on Saturday that Burns remained in the region.

“Contacts and cooperation with the mediators continue all the time in an effort to narrow the gaps and reach agreements,” Mossad said in the statement, which was distributed by Israeli Prime Minister Benjamin Netanyahu’s office.

Israel and Hamas, the militant Islamist group that rules the Palestinian enclave and has been locked in a war with Israeli forces since its deadly Oct. 7 rampage in southern Israel, have traded blame over the apparent deadlock in talks in the run-up to Ramadan, which begins on or around March 10.

A Hamas source told Reuters the group’s delegation was “unlikely” to make another visit to Cairo over the weekend for talks.

Egypt, the U.S. and Qatar have been mediating truce negotiations since January. The last deal struck was a week-long pause in fighting in November during which Hamas released more than 100 hostages and Israel freed about three times as many Palestinian prisoners.

Hamas blames Israel for the impasse in negotiations for a longer ceasefire and the release of 134 hostages believed still held in Gaza - saying it refuses to give guarantees to end the war or pull its forces from the enclave.

Mossad said Hamas was digging its heels in and aiming for violence in the region to spiral during Ramadan. Israeli officials have said that the war will end only with the defeat of Hamas, whose demands Netanyahu has called “delusional”.

Biden, who has repeatedly called for a temporary ceasefire, said in an MSNBC interview that it was “always possible” that a deal could be reached before Ramadan. But he did not elaborate.

While reiterating steadfast U.S. support for Israel’s right to defend itself, Biden told MSNBC his message to Netanyahu about the need to limit Palestinian civilian casualties is that he is “hurting Israel more than helping” by acting in a way “contrary to what Israel stands for.”

Asked whether he would be willing to return to Israel, where he visited in mid-October in a show of solidarity, to address lawmakers, Biden said “yes.” But he declined to elaborate.