Mark Smith, who was based in the British embassy in Dublin, said there was "no justification for the UK's continued arms sales to Israel".
Images of his resignation email sent to colleagues were posted online, with Mark Smith, who was based in the British embassy in Dublin, writing there was "no justification for the UK's continued arms sales to Israel".
Smith, who describes himself as an expert in arms sales policy, was a second secretary dealing with "counter terror", a relatively junior position in the foreign office (FCDO).
Issuing a follow-up statement, Smith said he had "written to the foreign secretary informing him of my resignation and urging him to urgently review the UK approach to the situation in Gaza", according to the BBC on Monday.
"Each day we witness clear and unquestionable examples of war crimes and breaches of international humanitarian law in Gaza perpetrated by the State of Israel," Smith wrote in the resignation email.
He said concerns regarding the legality of arms sales that he raised "at every level" of the FCDO were "disregarded", and accused the UK government of failing to have a "robust and transparent" arms exports licensing regime.
Legal review
An FCDO spokesperson said that while it did not comment on individual cases, the "government is committed to upholding international law".
"We have made clear that we will not export items if they might be used to commit or facilitate a serious violation of international humanitarian law," the spokesperson added in a statement sent to AFP on Monday.
After taking office last month, Foreign Secretary David Lammy ordered a legal review of whether UK-issued arms export licences to Israel were at risk of facilitating breaches of international humanitarian law.
"We will provide an update as soon as that review process has been completed," the FCDO said in its statement.
Lammy has previously indicated that there would be no "blanket ban" on arms sales to Israel, but that he would "consider the issues in relation to offensive weapons in Gaza".
The UK has issued 42 military licenses to Israel between October 7 -- since Israel's assault on Gaza began -- and the end of May, according to government data.
Since October 7, Israel's relentless bombardment and ground invasion has killed over 40,000 people, according to Gaza's health ministry.
*This story was edited by Ahram Online.
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