A British Foreign Office official working on counterterrorism has resigned in protest against arms sales to Israel, warning that the British government was “possibly involved in war crimes.”

Mark Smith wrote to colleagues on Friday that he had raised his concerns “at every level” in the State Department, including through an official whistleblower mechanism.

Mr Smith, who was based at the British Embassy in Dublin, added that he had only received basic confirmations.

The Foreign, Commonwealth and Development Office (FCDO) declined to comment on an individual case, but said the government was committed to complying with international law.

The resignation email, seen by the BBC, was sent to numerous mailing lists, including hundreds of government officials, embassy staff and special advisers to foreign ministers.

Mr Smith said he had previously worked for the Government on arms export licensing to the Middle East and that his colleagues were witnessing “clear and unequivocal examples” of war crimes and violations of international humanitarian law by Israel in the Gaza Strip “on a daily basis”.

“Senior members of the Israeli government and military have openly expressed their intent to commit genocide, and Israeli soldiers have filmed themselves deliberately burning, destroying and looting civilian property,” he wrote.

“Entire streets and universities have been destroyed, humanitarian aid is blocked and civilians regularly have no safe place to flee to. Red Crescent ambulances have been attacked, schools and hospitals are regularly attacked. These are war crimes.”

He said there was “no justification for Britain’s continued arms sales to Israel”.

The FCDO said Foreign Secretary David Lammy had launched a review “on his first day in office” to determine whether Israel was complying with international humanitarian law.

While hundreds of officials in the UK, Europe and the US recorded unprecedented levels of rejection Although they criticised their governments’ policies towards Israel in relation to the Gaza war, there are far fewer known cases of so-called resignations on principle, making Mr Smith’s case an extremely rare occurrence for the British government.

According to the email, he served as “Second Secretary for Counterterrorism” – a relatively low rank, but one in which he described himself as a “subject matter expert in the field of arms sales policy” after “a long career in the diplomatic service.”

His email continued: “Ministers claim that the UK has one of the most ‘robust and transparent’ arms export licensing systems in the world. But this is the opposite of the truth.”

“As a fully exonerated officer who raises serious concerns about illegality in this department, it is deeply disturbing that he is being ignored in this way. It is my duty as a public servant to raise this.”

Since 2008, Britain has issued licenses for arms exports to Israel totaling £574 million ($727 million), according to the Campaign Against Arms Trade (CAAT).

The British government recently downplayed the size of the offer, describing it as “relatively small” and expected to amount to £42 million ($53 million) in 2022.

Israel has repeatedly denied violating international humanitarian law in the Gaza Strip.

In response to previous cases of dissent among Western politicians over policy and arms supplies, the Israeli government declared that it wanted to defeat Hamas as a “genocidal terrorist organization that commits war crimes and crimes against humanity.”

In May, the chief prosecutor of the International Criminal Court (ICC) requested arrest warrants for war crimes against the Israeli prime minister and defense minister, as well as against senior Hamas officials. However, these have not yet been issued.

An FCDO spokesman said: “This government is committed to complying with international law. We have made clear that we will not export goods that could be used to commit or facilitate serious breaches of international humanitarian law.”

The spokesperson added: “The Secretary of State initiated an ongoing review process on the first day of his term to determine Israel’s compliance with international humanitarian law. Once that review process is complete, we will provide an update.”