Union flags fly at half mast over Parliament and Whitehall in memory of the victims of the atack on Manchester Arena, in London, Britain, May 23, 2017. REUTERS/Toby Melville

LONDON (Reuters) - Britain’s parliament said on Wednesday it would close to the public with immediate effect due to an increased security threat after Monday’s suicide bomb attack in Manchester.

Prime Minister Theresa May said on Tuesday that Britain now faced a ‘critical’ security threat - meaning another attack could be imminent - and ordered soldiers to reinforce armed police guarding public buildings and events.

“As a consequence all tours, events and banqueting will be cancelled with immediate effect. This arrangement will remain in place until the advice changes,” the parliament said on its website.

Parliament is not currently sitting, due to a national election taking place on June 8.