Benjamin Netanyahu has asked for "forgiveness" from Israelis for failing to return six hostages found dead in Gaza on Saturday, as Hamas warned more could be "returned to their families in shrouds" if a ceasefire isn't reached.
His comments came as intense street protests over his handling of negotiations entered a second night in Israel.
Pressure also mounted internationally as the UK suspended some arms sales to Israel, citing a risk of equipment being used to violate international law.
But Israel's prime minister struck a defiant tone, insisting its troops must control Gaza's Philadelphi corridor - a strategically important strip of land which is a sticking point in negotiations with Hamas.
Thousands of Israelis took to the streets on Monday in fresh protests called by hostages' families to express their anger at Mr Netanyahu's failure to bring home their loved ones after almost 11 months.
The Times of Israel reported that police were using considerable aggression at one protest outside the prime minister’s home in Jerusalem, including violently pushing protesters, throwing some to the ground, and dragging many away.
One member of the police squeezed the throat of a Times of Israel reporter, according to the newspaper.
The latest demonstrations come after hundreds of thousands of people took to the streets in protests across the country on Sunday, with some demonstrators blocking a major highway in Tel Aviv. Many wore Israeli flags and hung yellow ribbons - a symbol of solidarity with the hostages - from a bridge overlooking the Ayalon Highway.
A total of 97 hostages remain unaccounted for after being kidnapped by Hamas on 7 October last year.
Hamas said on Monday that hostages would be returned "inside coffins" if military pressure from Israel continues and added that "new instructions" have been given to militants guarding captives if they are approached by Israeli troops.
"Netanyahu's insistence to free prisoners through military pressure, instead of sealing a deal means they will be returned to their families in shrouds. Their families must choose whether they want them dead or alive," a spokesperson for the group said, without elaborating on what new orders had been issued.
Earlier on Monday, Israel's biggest trade union said hundreds of thousands of people had joined a general strike called to put pressure on the government to agree a Gaza ceasefire and hostage release deal with Hamas.
Despite this, Tel Aviv's Ben Gurion airport reported limited disruption and many restaurants and hospitality services operated as normal. Far-right Finance Minister Bezalel Smotrich boasted that Israelis had gone to work “in droves” and proved that they were no longer slaves to “political needs”.
Elsewhere, US President Joe Biden said Mr Netanyahu was not doing enough to secure a hostage deal and ceasefire with Hamas, amid reports suggesting a new proposal would be sent to the Israeli prime minister as "final".
Many accuse Mr Netanyahu of blocking a deal to prioritise his own political survival - a claim he rejects.
Mr Netanyahu's far-right allies have threatened to pull out of the coalition government, undermining his chances of staying in power, if he were to accept a deal tied to a permanent ceasefire before Hamas was destroyed.
US, Egyptian and Qatari mediators are trying to broker a ceasefire deal that would see Hamas release the 97 hostages still being held, including 33 who are presumed dead, in exchange for Palestinian prisoners in Israeli jails.
UK Foreign Secretary David Lammy said on Monday that the UK had suspended 30 out of 350 arms export licences to Israel, citing a "clear risk" the equipment could be used to commit serious violations of international law.
The affected equipment includes parts for fighter jets, helicopters and drones.
Mr Lammy said the UK continued to support Israel's right to defend itself, and this did not amount to an arms embargo.
Israel's Defence Minister Yoav Gallant posted on X, to say he was "deeply disheartened" by the move, while Foreign Minister Israel Katz said it sent a "very problematic message" to Hamas and Iran.
Meanwhile, funeral services for some of the hostages killed on Saturday have been held.
The mother of Hersh Goldberg-Polin - one of the hostages whose body was recovered by Israel on Saturday - spoke at his funeral and said she had been in "such torment and worry" about him for months.
Rachel Goldberg-Polin said it had been a "stunning honour" to be her son’s mother. Around the time of his kidnap, Hersh sent two texts to his family, writing: "I love you guys,” and "I’m sorry".
Mourners lined the streets in Jerusalem and Israel's President Isaac Herzog spoke to relatives at the funeral.
The Israeli military launched a campaign in Gaza to destroy Hamas in response to the unprecedented attack on southern Israel on 7 October, during which about 1,200 people were killed and 251 others were taken hostage.
More than 40,000 people have been killed in Gaza since then, according to the territory's Hamas-run health ministry.
