The SAS could lose a vital training base in the Far East if Jeremy Corbyn becomes the next prime minister, senior defence officials have warned.

Concerns have been raised about the future of the British garrison in Brunei after senior Labour figures called for a boycott following the country’s rulers’ decision to introduce death by stoning as punishment for homosexuality earlier this year.

The British military base in Brunei, the only remaining British presence in the Far East, is one of the Army’s major training centres, and its renowned Jungle Warfare Training School is used by the SAS and other British special forces units for intensive training exercises.

But the future of the base, whose five-year lease is due for renewal in February next year, would be in serious doubt if Mr Corbyn triumphs in next month’s general election, according to insiders at the Ministry of Defence.

Senior Labour figures, such as Emily Thornberry, the shadow foreign secretary, as well as gay rights campaigners have been highly critical of Brunei’s rulers after they sought to impose severe punishments against the country’s gay community.

Calls for Britain to cut ties with Brunei came after the country’s ruler, Sultan Hassanal Bolkiah, introduced strict new sharia laws in April which imposed the death penalty for a range of crimes, including homsexuality.