Leading Plaid Cymru politicians have called on the prime minister to sanction the Israeli government “without delay” over the conflict in Gaza.

Rhun ap Iorwerth and Liz Saville Roberts said “moral courage” was needed by Sir Keir Starmer’s government.

The United Nations has warned mass starvation across Gaza is causing a “dire situation”.

The Israeli government rejected a statement from the UK and 27 other countries earlier this week that called for an immediate end to the war. The UK government has been asked to respond.

The letter, addressed to Sir Keir Starmer and Foreign Secretary David Lammy, said “history will judge” politicians who did not do everything in their power to stop the unfolding situation in Gaza.

Ap Iorwerth, Plaid’s leader, and Saville Roberts, the party’s Westminster leader, said sanctions must include a complete arms embargo, and said they were deeply frustrated the “UK government’s deeds are not following its rhetoric”.

Earlier this week the Foreign Secretary, David Lammy, called the situation in Gaza “grotesque” and pledged to take further action if a change in behaviour was not seen from Israel.

The Plaid leaders urged the UK government to put pressure on other foreign powers so the UN takes “urgent and robust action”, and called for the recognition of Palestine as a state.

This week, more than 100 international aid organisations warned of mass starvation in Gaza, blaming an Israeli “siege” on food trucks carrying aid.

Meanwhile at least 1,054 Palestinians have been killed by the Israeli military while seeking food since 27 May, according to the UN.

Israel said 150 food trucks were collected by the UN and other agencies in Gaza on Wednesday with a further 800 waiting collection – but aid workers have said Israel has obstructed them from doing so.

Israel and the US say the system is necessary to stop Hamas from stealing aid, something the UN has not endorsed.

Elsewhere Montgomeryshire and Glyndwr Labour MP Steve Witherden, alongside Plaid Cymru MPs, were among 56 politicians who have written to cabinet politicians calling for an arms embargo on Israel and more transparency around what military parts were being exported abroad.