Alton Towers crash
The Smiler crash at Alton Towers left four victims with severe leg injuries Getty

Merlin Entertainments, the company behind Alton Towers, is expected to take a £3m hit as a result of the tragic Smiler rollercoaster accident that left four people seriously injured.

The firm will report results for the first half of the year on July 30 and City analysts expect the accident to have had a negative impact on performance.

Vicki Stern, analyst at Barclays, said: "We estimate that the incident on the Smiler rollercoaster will have negatively impacted performance from park closure for five days, slower volumes following re-opening and more promotional activity and some impact at Chessington and Thorpe Park due to other ride closures."

A total of 16 people were injured in the collision and, in addition to the expected £3m hit to revenue, Merlin is likely to face hefty compensation pay outs to those affected.

Chris Stevens, analyst at UBS, believes there could be downgrades to full year profits. He said: "We do not believe consensus or the market has correctly adjusted for the 'Smiler' accident at Alton Towers. There could be consensus earnings downgrades for 2015."

The Smiler rollercoaster, which cost £18m, may never reopen.

However, the company, which also owns Legoland and Madame Tussauds, is forecast to report an overall 3% increase in like-for-like sales in the period, with sales up 5.6% to £542m.

Mark Irvine-Fortescue of Jeffries said: "The stock is one of our top long ideas in the sector."