Reliable British government sources said early today that the figure had been reached after comparing Foreign Office lists from worried relatives with documents from the US immigration service and investigations by the Bureau of Alcohol, Tobacco and Firearms, which has been investigating the cult for eight months.
There was no news on the health of the Britons, who joined within the past two years. According to the FBI there are an unconfirmed number of dead members around the headquarters.
There are an estimated 110 'Branch Davidians' within the compound, which has been under siege since Sunday after four federal agents were shot dead in a 45- minute gunfight during a raid to arrest the cult leader, David Koresh, who believes himself to be Jesus Christ.
According to an affidavit filed by an FBI agent, all the adult members are alleged to have taken part in the gun battle in which thousands of rounds of ammunition were fired from automatic weapons, possibly including a .50 calibre machinegun.
David Hook, British vice-consul in Houston, visited Waco yesterday to inquire after the welfare of the Britons, believed to have been recruited by Mr Koresh during a UK visit. Until now it was thought only 16 Britons might be inside.
They are surrounded by at least 300 police and federal officials, who have armoured vehicles, a tank and a large array of weaponry. But the FBI says it does not intend to storm the building.