The Transport Salaried Staffs Association, which represents Thomas Cook employees, said it was "shocked and angry" at the scale of the job losses.
General secretary Manuel Cortes said: "This constant policy of slash and burn, with the axing of one in four stores and the loss of jobs, is simply self-defeating.
"The company needs new products if it to come to come to terms with the age of the internet and prosper in the 21st century.
"That is the only way to stop this spiral of decline which repeated bad management decisions over the past five years has led them."
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At least three children and 18 others - including members of the local police force - were among those who died.
The Foreign Secretary was unable to rule out the possibility of continuing to pay money into the EU when he spoke to Peston On Sunday.
He told Peston on Sunday: "The country is crying out for leadership from the Prime Minister. We want to know her vision."