Twelve defendants, including two British holiday reps, were due to go on trial this morning in connection with the deaths of Christianne Shepherd, seven, and her brother Robert, six, who suffered carbon monoxide poisoning in a Greek holiday apartment in October 2006.

But the case at Corfu Town Courthouse was postponed at the request of four of the defendants.

Paul Wood, the children's stepfather, read a statement saying: "We are all very disappointed that we will have to wait a further six months to see justice done."

The children were overcome by fumes while on a family holiday in Corfu.

Their father, Neil Shepherd, and his partner, Ruth Beatson, both fell into comas and were admitted to hospital, but survived the poisoning.

Richard Carson, 27, and Nicola Gibson, 25, who were both holiday representatives for Thomas Cook when the incident occurred, face charges in a Greek court of manslaughter and negligence.

Their trial was adjourned until February next year.

They are accused of causing manslaughter by negligence in relation to the children, and of causing bodily injury by negligence to Mr Shepherd and Ms Beatson.

Ten Greeks, including staff from the Louis Corcyra Beach Hotel in Gouvia, where the family were staying, were also due to be tried.

It is believed the tragedy was caused after carbon monoxide fumes leaked from a next-door room into the bungalow apartment the family had booked for a half-term break.

Mr Shepherd and Ms Beatson flew out to Corfu for the trial along with Robert and Christianne's mother Sharon Wood, who was in the UK at the time of the tragedy, and her husband Paul.

The family have previously said they believe Thomas Cook is "responsible for the events which led to the deaths" of the two children.

But a Thomas Cook spokeswoman said today: "We are confident that our colleagues acted properly and should not be blamed in any way.

"We continue to give them our full support and believe they will be vindicated by the court."

She added that Mr Carson is still employed by Thomas Cook as an overseas representative, while Ms Gibson no longer works for the company and has returned to the UK.

Carson and Gibson were among the four defendants who asked for an adjournment today on the grounds that their lawyer could not be present.

Mr Wood said the request for a postponement was "disrespectful" to the memories of the children.

He said: "Unfortunately Thomas Cook led us to believe that they wouldn't request for the case to be adjourned. Therefore they continue to play legal games.

"They continue to play these games with the memory of our children Christie and Bobby and we find this extremely disrespectful."

Mr Wood added: "The court decided to adjourn the case to February 4 2010 in spite of our objections and those of our legal counsel.

"We flew from England at great personal cost because we have faith in the Greek justice system.

"Our pain for the loss of our children cannot be expressed in words.

"We wish for the process to come to an end, doing justice to our children's memories so we can then try to rebuild our lives."

Mr Wood was accompanied to the court by his wife Sharon - Christianne and Robert's mother.

Her former husband Neil, and Ms Beatson, joined them on the steps of the court as he read the statement.