Boris Johnson has joined international calls for an “urgent de-escalation” of violence in the Middle East amid fears Israel and the Palestinians are sliding towards all-out war.

The Prime Minister issued a renewed appeal for an end to the “cycle of reprisals and retaliation” and for both sides to return to talks.

His call came amid the worst fighting since the 50-day war of 2014, with rockets fired from Gaza while Israeli forces have bombarded the territory with air strikes.

Speaking during a visit to County Durham, the Prime Minister said: “What everybody wants to see is urgent, urgent de-escalation.

“That’s what (Foreign Secretary) Dom Raab has been saying to his counterparts both in Israel and in the Palestinian Authority.

“I certainly think that everybody in the world wants to see an end to the cycle of reprisals and retaliation, they want to see de-escalation.

“They want to see both sides, sitting down and talking through and stopping the violence.”

Earlier the Foreign Office minister James Cleverly said Israel had a “legitimate right” to defend itself but must do so “proportionately”.

He told LBC radio: “We have got to remember that the military wing of Hamas, which is firing these rockets, is a proscribed terrorist organisation in the UK.

“There is no legitimate reason for these rockets to be fired, and we have demanded that they cease doing that.

“We recognise that Israel has a legitimate right to defend itself but must do so proportionately.”

Mr Cleverly, the minister for Middle East and North Africa, said Hamas has been firing rockets “indiscriminately” into civilian areas, which he called “completely unacceptable”.

“The simple truth is that the only way they can minimise civilian casualties is for the weapons to stop,” he told BBC Breakfast.

“That’s why we demand Hamas to stop flying the rockets and we are encouraging a de-escalation so that Israel does not feel the need to make military strikes into Gaza.

“And that’s the only way really that we are going to stop the casualties, stop the injuries and stop the deaths.”

Hamas and other militant groups in Gaza, claiming to be defending Jerusalem, have fired hundreds of rockets at Tel Aviv and other cities.

Israel has responded with air strikes targeting police and security installations, although the Palestinian authorities said there have been civilian casualties.

As many as 10 senior Hamas military figures were killed on Wednesday as Israel pressed ahead with a fierce military offensive, while Hamas and other groups showed no signs of backing down and fired rockets at Israeli cities.

The death toll in Gaza rose to 69 Palestinians, including 16 children and six women, according to the health ministry.

A total of seven people have been killed in Israel, including four on Wednesday.

The latest upsurge in violence has been triggered by tensions in Jerusalem during the Muslim holy month of Ramadan, with clashes at a holy site sacred to both Jews and Muslims.

Preparations for Eid al-Fitr, the Muslim holiday marking the end of a month of day-long fasting, have been sombre in Gaza, as residents brace themselves for further devastation and unrest.