By Keith Weir

LONDON (Reuters) - Blanket Olympic television coverage and canceled horse races in a soggy summer reduced the sums gambled in British betting shops, bookmaker Ladbrokes Plc said on Thursday.

The Olympics in London were hugely popular with Britons but this did not translate into a surge in business for bookmakers, as many of the sports in the Games do not attract large numbers of gamblers.

Ladbrokes, Britain's second-largest bookmaker, said amounts staked in its British betting shops fell 4.9 percent in the three months through September, covering the Olympics and Paralympics and when bad weather caused the cancellation of 38 horse racing meetings.

"You had 24 hours of free, high-quality TV sports and it went on for four or five weeks. People were watching that rather than going to betting shops," said Ladbrokes Chief Executive Richard Glynn. "It's a once in a lifetime thing."

Online gambling exchange Betfair Group Plc said last month Olympics mania had sapped interest in betting on soccer and horse racing in August.

Quarterly operating profit at Ladbrokes reached 49.2 million pounds ($79.5 million), barely changed from 49 million a year earlier. Net revenue rose 3.9 percent.

"Though the economic outlook remains uncertain, we remain confident in our delivery and are in line with the board's expectations for 2012," said Glynn.

Ladbrokes said first versions of its new online sports betting website had been successfully released and it planned to migrate customers on to the platform by the end of the first quarter of next year.

The company's first-half performance had been hit by problems in its digital business - comprising online, tablet and mobile - where profits halved, in contrast to rivals who have seen strong growth online.

It has been investing more than 50 million pounds on technology over the past two years and expects to start to see a payback from 2013.

Glynn said Ladbrokes would look at acquisitions only if the price were right and they did not embroil the company in regulatory problems.

Takeover talks with online gaming company Sportingbet Plc foundered last year over regulatory concerns related to business in Turkey.

William Hill, Britain's largest bookmaker, has now joined forces with GVC Holdings Plc for a 530 million pound takeover of Sportingbet, which won provisional approval this week from the Sportingbet board.

Ladbrokes shares, up 15 percent since first-half results in August, were little changed at 180.8p by 0830 GMT.

($1 = 0.6186 British pounds)

(Editing by Paul Sandle and David Holmes)