At least 25 Palestinians were killed in four Israeli air strikes on Wednesday in a part of Gaza under Hamas control since a shaky ceasefire took effect in October, health authorities said.

The Israeli military said its forces struck Hamas targets across Gaza after members of the Palestinian militant group fired on its troops in violation of the nearly six-week-old ceasefire. No Israeli forces were injured.

Hamas condemned the Israeli strikes as a dangerous escalation, and urged the United States to “honour its stated commitments and exert immediate pressure on Israel to enforce the ceasefire and halt its attacks”.

But a US official, who spoke anonymously, said Hamas was aiming to break the ceasefire and not fulfil its commitment to demilitarise.

“These desperate tactics will fail,” the official said.

Medical workers said 10 people were killed in the Gaza City suburb of Zeitoun, two in the Shejaia suburb to the east, and the rest in two separate attacks in Khan Younis in the southern Gaza Strip.