General Election campaigning has been suspended after the suspected terrorist attack that killed 22 people in Manchester.
Labour leader Jeremy Corbyn said he had spoken to Prime Minister Theresa May and they had agreed that all national campaigning would be suspended until further notice.
Mrs May will chair a meeting of the Government’s emergency Cobra committee on Tuesday morning.
Liberal Democrat leader Tim Farron called off an election visit to Gibraltar and the SNP postponed Tuesday’s planned manifesto launch.
Mr Corbyn said: “I am horrified by the horrendous events in Manchester last night. My thoughts are with families and friends of those who have died and been injured.
“Today the whole country will grieve for the people who have lost their lives.
“I have spoken with Andy Burnham, the mayor of Manchester, who has fully briefed me on the operational response in the city.
“I would like to pay tribute to the emergency services for their bravery and professionalism in dealing with last night’s appalling events.
“I have spoken with the Prime Minister and we have agreed that all national campaigning in the General Election will be suspended until further notice.”
Mrs May said: “We are working to establish the full details of what is being treated by the police as an appalling terrorist attack.
“All our thoughts are with the victims and the families of those who have been affected.”