Britain's main political parties suspended campaigning Sunday for this week's election after an attack in London left seven people dead -- although the UK Independence Party (UKIP) said it would carry on.

The truce is the second in the race for the June 8 vote, after campaigning was halted for several days following the Manchester concert attack on May 22.

But with the race tightening between Prime Minister Theresa May's Conservatives and the main opposition Labour party, the suspension is only for national events -- and is likely to last only a few hours.

"The Conservative party will not be campaigning nationally today. We will review as the day goes on and as more details of the attack emerge," a spokesman for the centre-right party told AFP.

Labour leader Jeremy Corbyn said: "The Labour party will be suspending national campaigning until this evening, after consultations with other parties, as a mark of respect for those who have died and suffered injury."

The Scottish National Party (SNP) said it was suspending national campaigning "this morning", adding: "Appropriate local campaigning will continue."

The smaller Liberal Democrats also followed suit.

However, Paul Nuttall, the leader of the pro-Brexit, anti-immigration UKIP, said: "I refused to suspend campaigning because this is precisely what the extremists would want us to do."

He added: "It is more important than ever for us to confront this evil with the democratic principles that have made this country what it is."