Victims' relatives and survivors gathered for the service

The families of two Taiwanese women who died in the crash called on the British Government to hold a public inquiry.

Relatives of the seven people who were killed joined survivors for the dedication of a memorial garden close to the Hertfordshire station where the tragedy happened.

A public service for the people of Potters Bar will be held at a nearby school during the afternoon, with several hundred people expected to attend.

In a statement the relatives of the Taiwanese pair, Chia-hsin Lin and Chia-Chin Wu, said: "Our hearts have been broken, our skies have turned grey."

Victims Agnes Quinlivan, 80 Austen Kark Jonael Schickler, 25, Emma Knights, 29 Chia-hsin Lin, 29 Chia-Chin Wu, 30 Alexander Ogonwusi, 42

"On the eve of Taiwan's Mother's Day such a loss is unbearable".

Investigations into the derailment are still going on, prompting anger from many relatives and survivors who want to know why the tragedy happened and the chance to claim compensation.

The general secretary of train drivers' union Aslef, Mick Rix, said it was appalling that after a year the cause of the disaster has not been revealed.

No trains were allowed to pass through the station while the memorial garden was opened at 1256 BST - the time of the crash.

Memories of crash remain Victims 'still waiting for answers'

A specially commissioned sculpture was unveiled and flowers laid in memory of the dead.

During the public service, which begins at a local school at 1430 BST, ten candles will be lit - seven for those who died and one each for the injured, the emergency services and the local community.

"This happened in the heart of the community in Potters Bar and a lot of people were involved and will remember that fateful afternoon very clearly," a spokesman for the Diocese of St Albans told BBC News Online.

'Terribly hurtful'

The first anniversary has led to renewed calls for more to be done to establish the cause of the tragedy.

The call for a public inquiry is backed by Louise Christian, the solicitor representing some of the families and survivors.

Author Nina Bawden, 77, who was severely injured and lost her husband Austen Kark, said it was "terribly hurtful" that nobody had been held to account.

Author's anger over Potters Bar

Bob Crow, general secretary of the biggest rail union the RMT, said: "Today we remember those who died and were injured at Potters Bar, and send our sympathies once more to their loved ones.

"But we also owe it to them to demand to know why this tragedy was allowed to happen."

Liberal Democrat transport spokesman Don Foster said the delay in reaching a conclusion was unacceptable.

He said: "A year on from Potters Bar there are still many questions unanswered about this and other rail crashes."

Mr Foster continued: "The travelling public deserves safe, affordable and reliable transport. Of these, safety must always be the number one priority."

Progress report

Neither Railtrack, the company at the time in overall charge of the track, nor Jarvis, the company maintaining that section of the track, have accepted responsibility for the accident.

Jarvis said the faulty points involved may have been sabotaged - although the Health and Safety Executive (HSE) said there was no evidence of this.

Its report also said the points were not up to standard and that nuts on other points in the area had not been fully tightened.

The HSE is due to publish a further progress report on its investigation at the end of May.