here are concerns that hundreds of the firms are using private numbers and personal details illegally to encourage people to gamble.
Online gambling has become a huge social problem, provoking alarming tales of debt, misery and family break-up.
Some of the firms have been accused of conning punters with misleading betting promotions and complex smallprint.
Any firms which target people with texts without getting permission are breaking the law and liable to fines of up to £500,000.
The Information Commissioners Office (ICO) has written to 400 companies demanding details on how they target people with texts.
The regulator wants to know where the companies got people's private information from and how many texts they have sent
The campaign is part of an investigation by the ICO into large numbers of spam texts linked to the gambling sector.
Last year, it emerged that a retired vicar from Scotland had been hit with a bill for more than £200 from a service linked to gambling.
Retired vicar George MacIntosh, 73, received 'TextPlayWin' text messages on his mobile phone which were costing him £4.50 a week. It appears the messages were triggered after he inadvertently responded to an unsolicited text from the company involved.
Online gambling companies appear to be buying lists of names and numbers from partner marketing firms. They also use these partner firms, so-called affiliates, to send out texts and then channel business to them.
The concern is that the neither the gambling firms nor their partners have carried out the necessary checks to ensure their targets have agreed to accept the texts
The ICO's anti-spam investigations manager, David Clancy, said: 'Companies must comply with the law when using people's personal information. Not knowing the law or trying to pass the buck to another company in the chain is no excuse.
'The public expect firms to be accountable for how they obtain and use personal data when marketing by phone, email or text.
'Fail to be accountable and you could be breaking the law, risking ICO enforcement action and the future of your business.'
The gambling sector is an area where the ICO has become aware of particular problems around affiliate marketing.
Mr Clancy said: 'It is thanks to consumers who've reported spam texts to us, as well as intelligence from other sources, that we've been able to progress our investigations to this stage.'
If businesses do not respond to the request for information, the ICO can use its powers to demand the information to be provided.
The ICO's website has an online tool where people can report spam texts.
A new code of practice has been launched by the ICO this month which sets out how organisations should explain to people how they're using their personal information
Just last month, another Government watchdog, the Competition & Markets Authority, announced its own investigation into the online gambling giants behind a £4billion a year gaming industry.
It is concerned the firms are misleading punters with offers that are too good to be true and impenetrable small print rules.
The CMA's Senior Director for Consumer Enforcement, Nisha Arora, said: 'Gambling inevitably involves taking a risk, but it shouldn't be a con.
'We're worried players are losing out because gambling sites are making it too difficult for them to understand the terms on which they're playing, and may not be giving them a fair deal.
'We are now investigating to see whether firms are breaking the law.
'Around 5.5 million Britons gamble online and they must be treated fairly. We' ve heard worrying complaints suggesting people may be lured into signing up for promotions with little chance of winning because of unfair and complex conditions.'
The Remote Gambling Association, which speaks for the firms, said: 'It's clearly right, irrespective of whether the affiliate marketing is related to gambling or any other product, that the ICO should take action if it believes there has been misuse of personal information.
'Affiliate marketing undertaken by third parties is important to the gambling industry, but we would obviously condemn any proven malpractice.'