The children's bodies were flown back to Manchester on Monday

West Yorkshire Coroner David Hinchliff promised to discover the cause and circumstances surrounding the deaths of Christianne and Robert Shepherd.

The girl, seven, and her brother, six, were on a half-term trip with their father and his partner when they died.

The coroner is dealing with the deaths as two separate inquests.

'Do my utmost'

The family, who are from Horbury, West Yorkshire, were staying in a plush holiday bungalow when the carbon monoxide gas, believed to be from a suspected faulty boiler, seeped into the property.

The children's father Neil Shepherd, 38, and his girlfriend, Ruth Beatson, 27, survived the poisoning last Thursday and are being treated at Pinderfields General Hospital in Wakefield, West Yorkshire.

Concluding a nine-minute hearing, Mr Hinchliff said: "I will do my utmost to ensure that, through all the channels available to me, the cause and circumstances of both Christie and Bobby's tragic deaths are fully, fairly and fearlessly investigated and the relevant facts are exposed to public scrutiny."

Sharon Wood and Neil Shepherd had previously separated

He added: "I will do my utmost to do this as quickly and efficiently as I possibly can."

He issued interim death certificates and burial orders before adjourning the proceedings to a later date.

Earlier, Coroner's Officer Jayne Melrose told the inquest how the family had gone to Corfu for a half-term break.

On 25 October they had "appeared fit and well" throughout the day, she said.

'Unwell'

She told the court how the family had gone out for a meal but after returning to the hotel, "it is understood that, within a short period of time, they individually started to feel unwell and the children were sick."

The children were found the next morning and were pronounced dead soon afterwards. Mr Shepherd and Ms Beatson were unconscious and in a coma.

She added that a Greek post-mortem examination gave the cause of death as carbon monoxide poisoning.

The court was told that further tests were under way to confirm this result.

The officer said formal identification of the children's bodies was carried out by Paul Wood, the second husband of the children's mother, Sharon Wood.

No members of the children's family attended the hearing.