Media playback is unsupported on your device Media caption Hundreds were caught up in the Belfast alert and some had to spend the night out of their homes

A bomb that partially exploded inside a car in Belfast city centre contained 60kgs (132lbs) of home-made explosives, police have said.

A masked gang hijacked a car at 21:30 GMT on Sunday, placed a bomb on board and ordered the driver to take it to a shopping centre.

It exploded as Army bomb experts prepared to examine the car left at the entrance to Victoria Square car park.

No-one was injured. Police have blamed dissident republicans.

Northern Ireland's chief constable Matt Baggott said there had been a "surge in dissident republican activity" recently.

Analysis Forcing a member of the public, a taxi or bus driver to transport a bomb to a target greatly reduces the risk of detection for those behind the attacks. In the past, many paramilitaries were arrested after being stopped while driving bombs into city and town centres across Northern Ireland. By forcing someone else to do it, that risk is removed. Even if the vehicle is stopped en route to its target, no member of the group responsible will be behind the wheel, and the driver won't be able to identify the masked men who forced them to be come bomb carriers. The tactic does not just reduce the risk of capture. It also protects those responsible for making and planting the device from the risk of early detonation as it is being transported to its intended target.

Last week, a bus driver was ordered to drive to a police station in Londonderry with a bomb on board.

On Saturday night, a van driver was threatened by two masked men and told to deliver a package to the same police station. On Monday, police said "nothing untoward" was found in the van.

Mr Baggott added the public would see a "significant increase in police presence" in Belfast city centre over the next few weeks.

"We need people who have changed their minds and come into the peace process to give us information," he said.

Assistant Chief Constable Drew Harris said if the bomb had fully detonated while the driver was in the car "he would have been killed outright".

He said it was a "terrifying, shocking experience for the poor driver" adding that those behind the device were "very reckless."

Media playback is unsupported on your device Media caption Assistant Chief Constable Drew Harris said the bomb partially exploded

Police said a silver Renault Laguna car, registration number CJZ 4697, had been hijacked in Jamaica Street, in the Ardoyne area of north Belfast.

It was then left at Victoria Square, opposite the city's main police station, and not far from Belfast's court complex.

A security operation began and premises were evacuated. The bomb partly exploded at about 23:15 GMT.

Northern Ireland's First Minister, Peter Robinson, said those behind the attack "have learnt nothing from the past".

He said: "They don't realise that this community wants to move on. We're working together, we're moving forward yet there are still some people out there who would seek to drag us back.

"They won't be successful, they won't break up what's going on in Stormont, they won't change the mind of our community and all they do is destroy the prospects people have of employment, of enjoying their life, and damage trade in Belfast and the surrounding areas."

Northern Ireland Secretary Theresa Villiers said it was "a reckless and callous attack" that could have put many lives at risk.

"Families have been forced out of their homes and commuters delayed in their journey to work by this attempt to attack ordinary people going about their daily business," she said.

Justice Minister David Ford said those behind the attack had nothing to offer.

"Those responsible for this attack have shown a total disregard for life, including that of the driver they forced to carry the device. They also have a disregard for the people of Belfast," he said.

"Had the device exploded en route it could have caused untold death and injury."

The deputy First Minister, Martin McGuinness, said that the threat would not impact the progress that had been made in recent years.

"It's not going to break up the institutions, it isn't going to undermine the political progress that has been made in the course of recent years, and the interesting thing is that two cities at the minute, appear to be bearing the brunt of these attacks - Belfast and Derry - places that have been transformed," he said.

"We get visitors coming here all the time who have been here maybe fifteen or twenty years ago, and they can't believe the change in both Belfast and Derry, and here we have a situation where a tiny number of people who are totally disconnected from local communities think they have the right to engage in these sorts of anti-people activities."

Image caption Traffic in the city centre was severely disrupted

Belfast Lord Mayor Máirtín Ó Muilleoir, of Sinn Féin, tweeted that people "won't be deflected from Christmas cheer by micro-groups of wreckers".

DUP councillor Guy Spence tweeted: "As the DUP rep on Belfast City Centre management board, I condemn last night's attack on Victoria Square. I urge anyone with info to contact PSNI."

SDLP MLA Fearghal McKinney said: "It's only good fortune that no-one was seriously injured, or worse, and those behind this have nothing to offer. Forty years of violence proved that."

BBC NI reporter Rick Faragher, who lives in the Victoria Square apartments, was among those who had to leave their home.

He said at about 22:00 GMT police told him there was a suspect car and he could not go back inside.

"I had my coat on, my phone with me, but the lights were still on in my flat, they told us to wait outside. They said they were not sure how long it could last for," he said.

"People were confused; they were not quite sure what was going on.

"There was a tremendous sense of frustration, it was particularly cold last night and there was quite a few of us out on the street.

"They let us back in just after five o'clock this morning."