Prime Minister David Cameron is returning early from his summer holiday to deal with the continuing riots in London.
A Downing Street spokeswoman said Mr Cameron was flying back from Italy overnight to chair the government's Cobra emergency committee.
London Mayor Boris Johnson has also cut short his family holiday and will be back Tuesday lunchtime.
It comes amid a third night of violence and looting across the city.
The BBC's Andrew Neil, writing on Twitter, said the riots were the prime minister's "first real crisis", adding "now we will find out if Mr Cameron is composed of the stuff of leadership".
Labour leader Ed Miliband is returning early from his holiday in Devon because of the riots.
In a statement, he said he was "shocked" by the scenes of violence and there was a need for a "pretty robust" response from police.
"This violence and vandalism is disgraceful criminal behaviour.
"What we need to see is the strongest possible police response to restore calm and security to our streets and for communities to work together.
"It is right that the prime minister is chairing Cobra. We need a co-ordinated response to ensure public safety and help those people who have lost homes and businesses."
Deputy Prime Minister Nick Clegg has cancelled a planned visit to Cornwall on Tuesday and will remain in London to attend the Cobra meeting at 09:00 BST, to be chaired by the prime minister.
Mr Cameron will then meet Home Secretary Theresa May and Metropolitan Police Acting Commissioner Tim Godwin.
A government spokesman said the prime minister has been monitoring the situation on "an hourly basis".
Violence erupted in Tottenham, North London, on Saturday after a peaceful protest against the fatal shooting of a 29-year-old local man, Mark Duggan, by police last week.
It spread over the weekend to Enfield and Walthamstow in north London and Brixton in the south.
Monday's violence started in Hackney after a man was stopped and searched by police but nothing was found.
Scotland Yard say 225 people have been arrested as violence spreade across London.
Businesses have been looted and set on fire in Camden, Clapham, Peckham, Ealing and Notting Hill.
Violence has also erupted in Birmingham, where shops in the city centre have been attacked and an unmanned police station in the Handsworth area is on fire.
Deputy London mayor Kit Malthouse told the BBC that while Mr Johnson was away, he had been in "constant touch" over events and had confidence in his policing team to do the job.
He had warned against "allowing these criminals to call the shots about what happens in London".
Mr Johnson's office would not disclose where the mayor was on holiday - saying they "don't discuss the mayor's private life and this extends to holiday plans".
But on Monday evening it emerged he would interrupt the family break to deal with the continuing disorder.
On Monday, Nick Clegg returned from his summer holiday in Spain to visit Tottenham, where violence erupted on Saturday night.
Speaking at a question and answer event organised by LBC radio, he rejected suggestions MPs should be recalled from their summer break: "Simply recalling Parliament won't solve the tensions on the streets of London.
"I totally back the very brave police officers and that's the priority right now, not politicians talking to each other at Westminster."
Lib Dem deputy leader and MP for North Southwark and Bermondsey Simon Hughes called on parents and other family members to keep their teenagers and young adults indoors.
"And there is just one simple message for young people," he added.
"Don't give in to the temptation to trash your own communities - these are the places which we all need for our future jobs, housing and prosperity."
Mr Duggan's death is being investigated by the Independent Police Complaints Commission.