By Daniel Hunter

The terrorist attack in Tunisia and the economic crisis in Greece are set to cost Thomas Cook £25 million in its full-year results, the travel agent has said.

It said the attack in Tunisia, in which 30 Brits were among 38 holidaymakers killed on a beach, would cost £20m. The costs come in the form of cancelled holidays, refunded holidays, alternate locations, and a slowdown in bookings for the rest of the summer.

"Since the end of the third quarter, our business has been impacted by significant external shocks," said Thomas Cook chief executive Peter Fankhauser.

"In response to the tragic events in Tunisia, we acted swiftly and decisively, evacuating more than 15,000 guests on approximately 60 flights and sending special assistance teams to offer logistical and compassionate support to customers and staff.

"In Greece, our local teams have worked diligently to ensure that economic issues do not disrupt our customers' holidays."

Thomas Cook posted a £3m profit in the second quarter of the year, compared with a £42m loss in the same period last year.