Tour operator Thomas Cook said health and safety procedures had been reviewed since the tragic death of two young siblings in one of their holiday apartments.
Bobby and Christi Sheperd, aged six and seven, died from carbon monoxide poisoning from a faulty boiler while on holiday in Corfu in 2006.
A Thomas Cook spokeswoman said: “Thomas Cook recognises that the pain caused by this terrible accident will never go away and must be still very hard for friends and family to bear.
“The systems which were in place in 2006, which were intended to prevent such a tragedy, have since been thoroughly revised and address the criticisms made by the jury.
“Thomas Cook works with dedicated specialist external health and safety experts to audit holiday properties. The health and safety of our customers is of paramount importance and we continuously review and strive to improve all our procedures.”
Three hotel employees of the Louis Corcyra Beach Hotel were found guilty of manslaughter in Greece but that investigation cleared Thomas Cook’s employees of any wrong doing.
Jurors at Wakefield Coroner’s Court this week returned a verdict of unlawful killing. They had already been told by West Yorkshire Coroner David Hinchliff that this was the only conclusion they could come to.
Speaking after the verdict, the children’s mother, Sharon Wood, said: “Thomas Cook said they offered our family practical and financial support. This is simply not true. Whilst we appreciate there were criminal convictions in Corfu, it is clear that Thomas Cook could and should have identified that lethal boiler.
“Thomas Cook put Christi and Bobby in that bungalow and I will always hold Thomas Cook responsible for their deaths.”
The coroner said he would use his powers to make recommendations to relevant organisations which he hoped would influence British and European law and practices in the holiday industry.