If US authorities do not comply within the two month limit, the businessman's 'unrestricted release' will be ordered, Venezuela's top court says.

Leonard Glenn Francis reportedly told a court in Caracas that he wanted to stay in Venezuela to appeal for political asylum and that he was suffering from metastatic kidney cancer.

Experts say one of them – a former oil tanker – could be a way for Iran to sidestep US sanctions by transporting petroleum under the flag of a warship.

Venezuela, which is under economic sanctions affecting the oil sector in particular, is facing a second wave of coronavirus.

President-elect Joe Biden's advisers have said he would retain sanctions but shift the focus of US strategy.