Britain's Prime Minister Theresa May returns to Downing Street in London, Britain, January 21, 2019. REUTERS/Hannah McKay

LONDON (Reuters) - British Prime Minister Theresa May on Monday condemned a car bomb attack in Northern Ireland’s Londonderry that has highlighted the threat posed by militant groups in the province.

Four men have been arrested over a car bomb attack on Saturday outside the city’s courthouse. On Monday, Northern Ireland police cordoned off two areas in Londonderry to examine two separate hijacked vehicles for potential security threats.

“I’m sure that the whole House will join me in condemning Saturday’s car bomb attack in Londonderry, and paying tribute to the bravery of the Northern Ireland police and the local community,” she said in parliament.

“This House stands together with the people of Northern Ireland in ensuring that we never go back to the violence and terror of the past.”