Jeremy Corbyn has condemned Israel’s killing of at least 27 Palestinians on the Gaza border as an “outrage” and attacked Western “silence” about the deaths.

In a message read out at a demonstration outside Downing Street, the Labour leader demanded that Theresa May support the United Nation’s call for an independent international inquiry.

Britain should also consider stopping the sale of arms to Israel that “could be used in violation of international law”, he said.

Mr Corbyn spoke out after at least nine more Palestinians were killed, and hundreds more injured, by Israeli gunfire, some reportedly shot in the head or upper body.

The latest deaths came a week after 18 Palestinians lost their lives when Israeli soldiers opened fire at similar demonstrations in support of a “right to return” to land lost to Israel in 1948.

The UN human rights spokeswoman, Elizabeth Throssell, has suggested the shootings could amount to wilful killing of civilians – a breach of the fourth Geneva Convention.

In his message, Mr Corbyn said: “The killing and wounding of yet more unarmed Palestinian protesters yesterday by Israeli forces in Gaza is an outrage.

“The majority of the people of the Gaza Strip are stateless refugees, subject to a decade-long blockade and the denial of basic human and political rights.

“More than two thirds are reliant on humanitarian assistance, with limited access to the most basic amenities, such as water and electricity.

“They have a right to protest against their appalling conditions and the continuing blockade and occupation of Palestinian land, and in support of their right to return to their homes and their right to self-determination.”

Mr Corbyn added that “firing live ammunition into crowds of unarmed civilians is illegal and inhumane and cannot be tolerated”.

“The silence from international powers with the responsibility of bringing a just settlement of the Israel-Palestine conflict must end,” he added.

"The UK Government must support the UN secretary-general's call for an independent international inquiry into the killing of protesters in Gaza and review the sale of arms that could be used in violation of international law.”

Boris Johnson, the foreign secretary, has said nothing since the first killings on 30 March, although his deputy, Alistair Burt, issued a statement saying he was “appalled by the deaths and injuries”. Mr Burt said: “There is an urgent need to establish the facts, including why such a volume of live fire was used and what role Hamas played in the violence.”

Israel came under pressure after a video showed a protester being shot in the back by an Israeli soldier as he walked away from the fence separating Gaza from Israel.

In other footage, Palestinians were shown being killed or wounded as they prayed, walked empty-handed towards the border fence, or simply held up a Palestinian flag.

According to reports in the Israeli media, the Israel Defence Forces’ rules of engagement allow live fire to be used against anyone who approaches the fence.