U.S. Secretary of State Antony Blinken arrived in Tel Aviv on Sunday on another Middle East tour to push for a ceasefire in Gaza but Hamas raised doubts about the mission just hours after he landed by accusing Israel of undermining his efforts.
The Palestinian militant group said it holds Israeli Prime Minister Benjamin Netanyahu responsible for "thwarting the mediators` efforts", delaying an agreement and exposing Israeli hostages in Gaza to the same aggression faced by Palestinians.
On his ninth trip to the region since the war began in October, Blinken will meet on Monday with senior Israeli leaders including Netanyahu, a senior State Department official said.
After Israel, Blinken will continue onto Egypt.
The talks to strike a deal for a truce and return of hostages held in Gaza were now at an "inflection point", a senior Biden administration official told reporters en route to Tel Aviv. "We think this is a critical time," the official said.
The mediating countries - Qatar, the United States and Egypt - have so far failed to narrow enough differences to reach an agreement in months of on-off negotiations, and violence continued unabated in Gaza on Sunday.
Israeli strikes killed at least 21 people in Gaza on Sunday, Palestinian health authorities said, including six children and their mother in an airstrike on a house in the central city of Deir Al-Balah. The youngest was aged 18 months, their grandfather Mohammed Khattab told Reuters as relatives later gathered around the bodies, wrapped in white shrouds.
"What was their crime? ... Did they kill a Jew? Did they shoot at the Jews? Did they launch rockets at the Jews? ... What did they do to deserve this?" asked Khattab.
There was no immediate comment from the Israeli military. Israel has denied targeting civilians as it hunts down Hamas militants, accusing the group of operating from civilian facilities including schools and hospitals. Hamas denies this.
The Israeli military said it destroyed rocket launchers used to hit Israel from the southern Gaza city of Khan Younis, the scene of intense fighting in recent weeks, and killed 20 Palestinian militants.
In the occupied West Bank, where violence has escalated since the war in Gaza broke out in October last year, an Israeli man died from wounds sustained in an attack, according to a hospital spokesperson.
