Gambling firms could use GPS to target "vulnerable" customers with offers, experts have warned. 

Firms could use location services to link a customer with ongoing events and send them targeted alerts. 

The technology raises the prospect of attendees at a football match being sent push notifications encouraging them to bet on the game they are watching.

Charity GambleAware said that companies "have the ability to collect significant amounts of customer data, including their location". 

"While some progress is being made to use customer data to identify and minimise gambling-related harm, much more needs to be done to tackle unacceptable marketing and advertising," said Marc Etches, the organisation's CEO.

Dr Mark Griffiths, distinguished professor of behavioural addiction and director of the international gaming research unit at Nottingham Trent University said that he had "no doubt that such a practice exists and is being used", having first predicted it 11 years ago. 

"I would always have concerns if the individuals being targeted are known to be vulnerable," he told the Daily Telegraph.

"Gambling companies often target their 'VIP' players, i.e. their heaviest spenders, and some of these are likely to be problem gamblers."

An spokesman for the information commissioner said: "If an organisation is processing people’s personal data in order to target online advertising at them, it needs to do so fairly and in accordance with the transparency requirements of data protection law. 

"Transparency is essential in allowing people to exercise their fundamental privacy and data protection rights.”

The warning came as bookmakers predicted a record amount would be spent on betting on this year's world cup. 

A spokeswoman for Ladbrokes said the tournament was set to be "the most popular World Cup the UK betting industry has ever seen". 

Rival bookmaker William Hill predicted that around £1bn would be wagered on the tournament by British gamblers. 

A spokesman added that the company did not tailor customers' offers to their geographical location.

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