Holiday giant Thomas Cook has warned over profits after sales were hit by the European heatwave.

The firm said that the prolonged period of hot weather across the continent meant more people spent June and July enjoying the sunshine at home and put off booking their holidays abroad.

Thomas Cook said that it now expects to deliver full-year underlying operating profit of around £280 million, down from previous estimates of £323 million.

The firm said that a slowdown in customer bookings during June and July extended into August, leading to higher-than-normal levels of promotional activity.

This "exacerbated pressure on margins", Thomas Cook added.

Thomas Cook makes all of its annual profits in the summer months but it also warned that the impact of the heatwave "is continuing to be felt into winter trading".

Boss Peter Fankhauser said: "Summer 2018 has seen a return to popularity of destinations such as Turkey and Tunisia. However, it has also been marked by a prolonged period of hot weather across Europe.

"This meant many customers spent June and July enjoying the sunshine at home and put off booking their holidays abroad, leading to even tougher competition and higher-than-usual levels of discounting in the 'lates' market of August and September.

"Our recent trading performance is clearly disappointing."

Shares in Thomas Cook plunged 28% following the profit warning.