The first loyalist march in Dublin since Partition had to be rerouted after thousands of republican protesters rioted in the centre of the Irish capital on Saturday, with several Irish police among 40 people injured.

The main thoroughfare, O'Connell Street, became a battle zone as up to 2 000 rioters tore up building materials being used in major renovation work in the road and hurled them at Irish police. Shops and hotels closed their doors, and at least three Irish police officers were taken to hospital as rioters hurled scaffolding poles, bricks, slates and rocks at their lines.

Violence raged throughout the afternoon as protesters opposed to the Love Ulster rally, involving Orangemen and relatives of Irish Republican Army (IRA) murder victims, fought running battles with Irish police. Cars were set alight and fireworks thrown at police. Shops near O'Connell Bridge were looted as the riot squad combined with a mounted unit initially prevented demonstrators, some of whom were chanting "IRA, IRA", from crossing the River Liffey.

Among those injured in the clashes was veteran Irish television reporter Charlie Bird. There were reports the RTE journalist was attacked by a mob outside a hotel in O'Connell Street. A photographer was also set upon by a gang on the steps of the Gresham hotel.

The chaotic scenes took place during a weekend when Dublin was meant to be showcasing itself as a world tourist destination. Thousands of tourists were in the city for Sunday's Six Nations rugby international between Ireland and Wales, and for the Jameson Dublin International Film Festival.

After an hour-long stand-off, the march headed by unionist victims' spokesperson Willie Frazer was stopped from its proposed route along O'Connell Street. Unable to clear the area of demonstrators, Irish police ordered loyalist marchers and their three bands on to buses and made them drive over to the Dail.

Irish police tried several times to remove the protesters, many of whom hid their faces with Celtic scarves, from O'Connell Street, but they reassembled in side streets. As the rioting continued on the northern side of the Liffey, the loyalists protested outside the Dail gates at about 2pm, the tunes of the Orange bands echoing to empty streets that the police had cordoned off.

By 3pm, the rioters had forced their way across O'Connell Bridge where there were further clashes with riot officers. A car was set alight in the middle of Nassau Street while a small group of rioters smashed up the headquarters of the Progressive Democrats, the junior partner in the ruling coalition. During the attack on the party office, the rioters used wheelie bins to smash windows and damage the front door. Rioting also erupted in Temple Bar, the city's main tourist quarter.

A spokesperson for An Garda Siochana said that by early afternoon six people had been taken to hospital, including the three Irish police officers, and 12 people arrested. But the final injury figure was potentially much higher. The chaos was largely due to demonstrators vastly outnumbering those deployed to police the rally.

Ruairi O'Bradaigh, president of republican party Sinn Fein, which organised the protest against the Love Ulster rally, compared the scenes to riots outside the British embassy in 1981 over the republican hunger strike at the Maze.

"I haven't seen anything like this for 25 years; in fact, this is much worse. They [the authorities] underestimated the depth of resistance to this march," said the veteran republican leader, as fireworks exploded and bottles smashed at garda lines beside the statue of protestant nationalist leader Charles Stewart Parnell.

One of those protesting against the loyalist march, Sean Fallon, who described himself as an ordinary GAA-supporting non-political Dubliner, said: "If the loyalists had just come down and laid a wreath somewhere and then met a government minister, I wouldn't have minded. But to try and walk down our main street waving the Union Jack, playing Orange tunes and generally rubbing our noses in it is going too far. That's why I'm here."

The Love Ulster rally was organised by the South Armagh-based Families Acting for Innocent Relatives. One speaker, the Democratic Unionist MP Jeffrey Donaldson, said the trip to Dublin had been worth it because people exercised their civil rights. -- Guardian Unlimited © Guardian Newspapers Limited 2006