The International Criminal Court's chief prosecutor, British barrister Karim Khan, has lost access to his email and his bank accounts have been frozen since Donald Trump slapped sanctions on him in February.

Trump imposed strict sanctions on the ICC, the highest criminal court in the world, after a panel of judges issued arrest warrants for Israeli prime minister Benjamin Netanyahu and his former defence minister Yoav Gallant in November.

One reason the the court has been hamstrung is that it relies heavily on contractors and non-governmental organisations. These businesses and groups have curtailed work on behalf of the court because they are concerned about being targeted by US authorities, according to current and former ICC staffers.

Microsoft, for example, cancelled Mr Khan’s email address, forcing the prosecutor to move to Proton Mail, a Swiss email provider, ICC staffers said. His bank accounts in the UK have been blocked.