Court officials said the judge heard the charges against the three men - BBC correspondent Rageh Omaar (pictured), producer Robin Barnwell and cameraman Frank Smith.

The trial has been adjourned until Sunday.

They were arrested in May after returning from the remote mountainous south-east of Yemen, where they filmed members of a tribe which has recently kidnapped a number of foreigners.

The crew were picked up at a military check-point and taken first to the Ministry of Interior, and then to the Attorney-General's office. They were later moved to a hotel in Sana'a.

The Yemeni authorities said they were not given permission to visit the area they filmed in.

However, the BBC said the three were working in Yemen with the appropriate accreditation and were engaged in legitimate journalism. It has urged the authorities to allow them to return to Britain immediately.

A Foreign Office spokesman said Britain would maintain pressure at the highest levels until the journalists were freed.