The mother of Israel's longest missing-in-action soldier is to lobby the British government to release secret files to help trace her son after 30 years.

This Monday marked the 30th anniversary of the Battle of Sultan Yacoub during the 1982 Lebanon war, when Zachary Baumel, Tzvi Feldman and Yehuda Katz went missing. Miriam Baumel spoke of her son at a special ceremony in Jerusalem this week.

Next week, Mrs Baumel will meet officials at the Foreign Office in London to seek further information that she claims could identify her son's whereabouts in Syria, where the soldiers are thought to have been taken, allegedly under the gaze of British diplomats.

Last year, the Foreign Office, after an FoI request from Manchester lawyer Daniel Berke, on Mrs Baumel's behalf, released some documents but said others remained secret to prevent a deterioration of diplomatic relations with Bashar Assad.

Mr Berke said: "It is clear there is other information; we can't determine if it is relevant because large parts of the material they have given us to date is redacted."