The Guardian reported on Thursday that campaigners have issued warnings to directors of 20 arms manufacturers based in the UK, warning them of criminal liability for their involvement in supplying military equipment to "Israel".

The Campaign Against Arms Trade (CAAT) and three other advocacy groups penned a letter directly addressing directors of firms contributing components to "Israel's" F-35 fighter jets, which have been utilized in airstrikes over Gaza.

Citing the 2001 International Criminal Court Act, the letter states that UK law prohibits engagement in activities ancillary to war crimes or crimes against humanity in foreign territories. 

Among the targeted companies are the UK branches of Lockheed Martin, a principal manufacturer of the F-35, and BAE Systems, responsible for a significant portion of each jet. Also included is Northrop Grumman, a US subcontractor involved in the F-35 program.

Read more: Pro-Palestine groups block UK weapons factories that ship to 'Israel'

The Global Legal Action Network (GLAN), War on Want, and the International Centre of Justice for Palestinians join CAAT in highlighting war crimes and atrocities committed by the Israeli regime in Gaza. 

The campaign groups have expressed readiness to engage in discussions with the implicated companies but have not ruled out pursuing legal action. Options include filing complaints with the Metropolitan Police or initiating private prosecutions should police action not be forthcoming.

Dearbhla Minogue, a senior lawyer with GLAN, told The Guardian that individuals involved in arms transfers to "Israel" may face criminal consequences irrespective of governmental policies permitting such sales. 

"The fact that they are hiding behind a licensing system which is unfit for purpose will not protect them if and when they face a jury of their peers because ordinary people can see through politicians’ obfuscation," she said.

Read more: British arms sales permits to 'Israel' drop to 13-year low: Reuters