A strong Cheltenham Festival helped bookmaker William Hill get off to a good start to its year.

The country's largest gambling firm group sales lifted by 9% in the first 17 weeks to 25 April compared to a year ago, boosted by a 16% jump in online revenue, the fastest-growing part of the industry.

The business, which rebuffed a £3.2bn ($4.1bn) takeover attempt last summer, said betting in the period was helped by favourable horseracing results, including the four-day Cheltenham Festival in March, which sees £350m wagered across the industry.

But it added football results, which saw favourites such as Chelsea and Tottenham continue to win matches, were "lower than expectations".

The business also said that total net sales at its betting shops, which accounts for the majority of its revenues, had grown by just 1% over the period.

However, the group said its trading was in line with market expectations for the year, and that it was on track to deliver £40m of cost savings by the end of 2017.

Chief executive Philip Bowcock said: "It has been a positive start to the year for William Hill across the board. Our online business continues to deliver growth thanks to the improvements in product, user experience and marketing we have made."

Betting firm mergers

Bowcock, was previously the group's chief financial officer, before former boss James Henderson left the group with immediate effect in July after poor trading.

An offer for William Hill by rivals Rank Group and 888 collapsed in August after the market leader twice rejected their bid as undervaluing the business.

The sector is going through a period of consolidation which threatens the dominance of William Hill, which runs more than 2,300 outlets in the UK.

Betfair and Paddy Power agreed to merge in 2015, online gambling business GVC bought rival Bwin.Party and Ladbrokes and Gala Coral are also combining.

The sector is also in the middle of costly upgrades to its online betting platforms, a part of the industry that is expanding rapidly.