Mrs Wood visited the mortuary for a second time

Christianne Shepherd, seven, and her six-year-old brother Robert died on Thursday at their holiday bungalow.

The hotel owner, manager and two maintenance staff face up to five years in jail if convicted of manslaughter.

Kostas Dendrinos of Corfu's Association of Hotel Managers said accommodation on the island should not be judged unsafe.

"This occurred in a hotel that had been operating since 1964," he said.

"It is run under serious management and according to all safety rules and regulations both from the European Union and tour operators."

It should not have happened, but with one million visitors a year, it did not mean resorts in Corfu were not safe, he added.

British tour operators have sent an independent gas expert to the resort to check the safety of other similar appliances.

And campaigners in the UK are calling for tougher checks on accommodation used by package holidaymakers.

Greek travel agent Vassilis Kontos, of Corfu Holidays, said although this should be treated as an isolated incident, extra safety checks would take place on the island during the winter.

Sunday prayers

The BBC's Malcolm Brabant said the children's deaths have sent a wave of shock and panic through the Greek holiday industry, with hoteliers worried about the impact on tourism - upon which Corfu's economy is heavily dependent.

And a visit to Corfu by the Greek Tourism Organisation's chief was part of a damage limitation exercise, our correspondent added.

Sharon Wood visited the hotel where her children died

The children's father, Neil Shepherd, 38, who was found alongside his children in the hotel room, has become fully conscious for the first time, according to hospital staff.

His partner Ruth Beatson, 27, who was also poisoned, has been taken out of intensive care.

She has been told by her mother about the deaths of the children but it is unclear whether Mr Shepherd has been informed.

Hospital manager Ioannis Manzaropolous said the couple are unlikely to suffer long-term damage to their health.

The property met all of the Federation of Tour Operators' requirements Thomas Cook Campaigners urge gas safety Q&A: Gas safety and travel

Prayers have been said for Christianne and Robert at services in Corfu and their home in West Yorkshire.

Services took place at Wakefield Cathedral, West Yorkshire, and the Anglican Holy Trinity Church in Corfu.

Father Clifford Owen told worshippers in Corfu the thoughts of the island's residents were with the classmates of the two dead children, who face the grief of returning to school after the half term holiday without their friends.

Christianne and Robert's mother, Sharon Wood, 35, had lived with the children in Horbury.

Mrs Wood has visited the Louis Corcyra Beach Hotel, in Gouvia village, where her children died and was said to be inconsolable.

She made a second visit to the mortuary on Sunday with her husband Paul, where she spent about 40 minutes inside the building.

A pathologist said carbon monoxide poisoning was the cause of death and the investigation is focusing on the room's gas boiler and air-conditioning.

Tour operator Thomas Cook said the latest audit of the hotel showed "the property met all of the Federation of Tour Operators' requirements".