The British government threatened to defund the international criminal court and leave the Rome statute that set it up if it pressed ahead with plans to issue an arrest warrant against Benjamin Netanyahu, the ICC’s prosecutor, has claimed.

Karim Khan made the allegation in a submission to the court defending his decision to prosecute Israel’s prime minister.

Khan does not name the individual who made the threats, saying the call on 23 April 2024 was with a British official, but reports have suggested the caller may have been the then British foreign secretary, David Cameron. Khan said the official had argued that issuing arrest warrants against Netanyahu and Yoav Gallant, the former Israeli defence minister, was disproportionate.

Khan also claimed that in April 2024 he was warned by a US official there would be disastrous consequences if he were to issue the warrants, but Khan – faced with calls to delay – insisted during the call there had been no sign the Israeli government was willing to cooperate with the ICC or change its behaviour.

He claimed that in a further call on 1 May the US senator Lindsey Graham warned him that applying arrest warrants meant Hamas may as well shoot Israeli hostages.

Khan said he had learned for the first time about sexual misconduct allegations against him on 2 May. He said that on 6 May a third party revealed that someone without the alleged victim’s consent had issued a complaint about his behaviour to the court’s watchdog, the internal oversight mechanism. When the victim said she did not wish to pursue an investigation the matter was dropped until an anonymous account on X started to reopen the allegations in October, he said.

Khan’s submission seeks to portray him as acting neutrally throughout and not seeking to advance his personal interests. He said the plan to issue the arrest warrant preceded the allegations against him.

He added that it would be wrong of the applicants to rely on conjecture from select media reports in order to advance unsupported assertions that there were grounds for disqualification, insisting his preparation for the case was meticulous.

It is understood that Khan insisted on sending a full and pugnacious 22-page response to the Israeli request for dismissal of the warrants after he read what he regarded as a relatively tame response that was initially drafted.

He said he had assembled a panel of experts on international law to assess whether or not the ICC had jurisdiction and if a case should be brought against Netanyahu, Gallant and three Hamas officials.