Travel firm Sun4U has collapsed, leaving approximately 1,200 customers stuck abroad.
The firm's website said it had ceased trading and advised people to contact claim handlers for Abta - The Travel Association.
Most of the company's stranded customers are said to be in Spain.
Abta said those with Air Travel Operators' Licensing (Atol) packages should be able to continue with their holidays as planned.
A spokesman said: "There are approximately 1,200 people away at the moment and most of them are in Spain."
BBC News - Holiday firm Sun4U collapses stranding 1,200 people
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