The mother of two children who died of carbon monoxide poisoning while on holiday in Corfu said today: "I will always hold Thomas Cook responsible for their deaths."
Sharon Wood spoke out after an inquest jury concluded that the tour operator "breached their duty of care" over the deaths of Bobby and Christi Shepherd, aged six and seven.
Speaking at the end of a two-week inquest hearing in Wakefield, West Yorkshire, the family's barrister Leslie Thomas QC said Thomas Cook should "hang its head in shame".
Thomas Cook responded by said everyone at the firm was "shocked and deeply saddened by the tragic loss" of the children but said its systems had been " thoroughly revised and address the criticisms made by the jury".
Bobby and Christi, from Horbury, near Wakefield, died at the Louis Corcyra Beach Hotel on the Greek holiday island when they were overcome by fumes from a faulty boiler.
The jurors at Wakefield Coroner's Court had already been told by West Yorkshire Coroner David Hinchliff that the only conclusion they could come to was unlawful killing.
The foreman also read out a series of conclusions which included how Thomas Cook had been misled by the hotel about its gas supply but also how the holiday giant's health and safety audit of the complex was inadequate.
Mrs Wood paid tribute to her "beautiful angels" as she made an emotional statement outside court, flanked by the children's father, Neil Shepherd, her husband, Paul, and Mr Shepherd's wife, Ruth.
Mr and Mrs Shepherd were with Christi and Bobby on the half-term holiday in October 2006 when the tragedy happened.
They were found unconscious next to the two dead children in a bungalow in the hotel grounds.
Mrs Wood said: "For everyone whose lives Christi and Bobby touched, I am hugely relieved that our fight for justice is over. We asked for lessons to be learned from our children's deaths; it will now fall to the coroner's recommendations to force Thomas Cook to act more responsibly in future.
"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.
"I would also like to say that there can never be true justice for the deaths of my two innocent children, their whole lives ahead of them.
"But as a family we feel that our legal team, the coroner, the jury and our MP Mary Creagh have done Christi and Bobby proud, and brought the tragedy finally to a respectful conclusion. Rest in peace now, our beautiful angels."
Mr Shepherd accused Thomas Cook of failing his family and refusing to answer questions about the tragedy for nearly a decade.
A number of former employees gave evidence at the inquest and declined to answer questions, exercising their legal right not to incriminate themselves.
Speaking outside Wakefield Coroner's Court, Mr Shepherd said: " From start to finish, Thomas Cook have hidden behind a wall of silence and they have refused to answer any questions for almost nine years.
"Thomas Cook are not blameless; we are disappointed they have refused to apologise to us.
"What is the point of a health and safety policy if it's not followed? What is the point in health and safety orders if they are not carried out by qualified and vigilant staff?
"Thomas Cook failed our family. That boiler room should have been checked. Ruth and I nearly died in that bungalow.
"The bottom line is, had Thomas Cook followed its own policy, Christi and Bobby would be alive today."
Leslie Thomas QC, who was representing the family following a battle for legal aid which went all the way to Prime Minister David Cameron, said in a statement outside court: "Thomas Cook, you are a multimillion-pound operation. You take money from families like this family, who expect to go on holiday and have the time of their lives.
"They don't expect to return from holiday with their children in coffins because Thomas Cook staff failed to properly check the standards of the hotel they stayed in.
"These children, the jury have found, were killed unlawfully as the result of criminal negligence. No explanation has been provided as to how this happened.
"Thomas Cook should hang its head in shame as a result of these deaths. The families of Christi and Bobby have waited nearly nine years for an apology - they are still waiting.
"When invited to apologise last week, the chief executive of Thomas Cook said 'I have nothing to apologise for'. Well, Mr Frankhauser, today this jury found that your staff failed to carry out proper monthly health and safety audits.
"Your staff were not given proper training. Your safety checks were not carried out vigilantly. We ask, will you say sorry now?"
A Thomas Cook spokeswoman said: " Everyone at Thomas Cook was shocked and deeply saddened by the tragic loss of Robert and Christianne Shepherd in 2006. 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 Greek authorities launched a thorough criminal investigation in 2010 which found three of the Louis Corcyra Beach Hotel employees guilty of manslaughter; that investigation cleared Thomas Cook's employees of any wrong doing. The Coroner had directed the jury that the only conclusion to reach was unlawful killing as legally it had to be consistent with the Greek verdicts.
"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."
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.
He asked for representations from the lawyers present by the end of July and said he would deliver his recommendations later this year.
Mr Hinchliff then said to Mr Shepherd, Mrs Wood and their families: "You have my eternal sorrow for what has happened to you. I don't think any one of us can begin to imagine the sorrow and grief you have gone through and continue to go through."