Thirteen people were killed in the French port of St Nazaire yesterday when a crowded gangway leading to the brand new Queen Mary 2 - the world's largest passenger ship - collapsed. Thirty-two others were injured, 10 of them severely.

More than 40 visitors were walking on to the liner across a gangway stretching up to 25 metres above the ground when it collapsed under them.

'They fell to the ground and then the scaffolding collapsed on to them,' said a witness.

Joel Batteux, the mayor of Saint-Nazaire, where the vessel is being completed, said: 'The town is experiencing a cruel grief. Everyone's lives rest on the shipworks. Everyone has a relative or a friend who works here. The town has never known such a tragic moment.'

The cause of the disaster was unclear, but accident investigators were due to be working through the night to try to establish what had caused the 12-metre wide gangway collapsed just four days after it had been installed.

The accident happened at 14.22 when a large number of relatives and friends of the shipyard workers were making their way on to the liner for a tour of the ship.

Jason Schmitt, worker who was on the gangway when it collapsed, survived the fall and was able to walk away with only minor injuries. His mother, who had accompanied him for the family tour, was also unhurt.

'I fell about 20 metres. There were a pile of injured and dead at the bottom. I don't know how many. But I found I was able to walk and move,' he told French television in an interview from the local hospital. 'There were shipyard workers and their families among the dead.'

Accident investigators have begun an official inquiry into the cause of the collapse. The gangway was put in place by specialist French firm Endel, a unit of French utilities giant Suez. The company said it was designed to hold far more people than were on it when it collapsed.

French president Jacques Chirac is to visit the site of the accident today.

The Queen Mary 2, which is due to sail from France to Britain in the next few weeks, is in dry dock during the final stages of its construction. It will feature a planetarium, 22 elevators and the world's largest floating library.

The £500 million liner - the world's longest, tallest and most expensive passenger ship - is being built by Alstom Marine's Chantiers de l'Atlantique for the British ship operator Cunard Line, which is owned by Carnival Corp. Around 800 companies, most of them French, have also been involved in the project.

However, the construction has been dogged by controversy. There were complaints when it was decided that the ship would be built in France and not Britain, and the row was compounded when the Queen agreed to take part in an elaborate naming ceremony planned for the QM2 at Southampton on 10 January, after it arrives from St Nazaire.

The liner has already generated huge interest. At least 150,000 people have written to Chantiers de l'Atlantique asking to come aboard for a look. The three earlier Cunard 'Queens' were all built in Britain, on the Clyde.

The largest cruise ship ever built

· The Queen Mary 2 is the largest passenger cruise ship ever built - at 1,132ft long, the vessel can carry 2,620 passengers.

· The QM2 is capable of speeds up to 30 knots (34mph).

· Carrying 1,253 crew, the ship has 1,310 cabins, including four royal suites and six penthouses.

· The standard cabins, at 194 sq ft, are the largest of any British-registered passenger ship.

· The main entrance is a six-storey grand lobby atrium, featuring a grand staircase and interior glass lifts.

· There are six restaurants and a terrace pool and bar, a 1,094-seater theatre, a cinema which converts into a planetarium and a ballroom with the largest dance floor at sea.

· There is a nightclub, disco, bars, shops, a casino, library, photo gallery and a video game arcade.

· The ship has a 20,000 sq ft health club, children's play zones, five swimming pools, 'drive-in' movies shown on deck and an art gallery.

· The first sheet of steel was cut in January 2002 and the keel-laying ceremony was held in July 2002.

· The £550 million Cunard flagship was constructed at the Alstom Chantiers de l'Atlantique shipyard in St Nazaire, France.

· The QM2 is due to arrive in Southampton next month, with a naming ceremony taking place at the port on 10 January 2004.