The bookmaker Betfred has been fined nearly £2.9m for failings in its social responsibility and money-laundering controls, after accepting tens of thousands of pounds from gamblers without performing adequate safety checks.

One customer was allowed to lose £70,000 over a 10-hour period just a day after opening their account, the Gambling Commission said.

Another was only subjected to controls to ensure they were gambling safety after losing £10,000. The next interaction did not occur until four months later when the customer had deposited £323,715 and lost £69,371. The regulator also identified flaws in the company’s controls to prevent money laundering.

Betfred, which is owned by the billionaire Tory donor brothers Fred and Peter Done, will pay a £2.87m penalty. That is the equivalent to approximately two days of revenue for the company, which paid the brothers a £50m dividend last year.

The bookmaker will also receive an official warning from the Gambling Commission.

Leanne Oxley, the commission’s director of enforcement and intelligence, said: “This is a further example of us taking action to investigate and sanction alarming failures.

“We expect this gambling business and all other licensees to review this case and look closely to see if they need to make further improvements to demonstrate active compliance. Where standards do not improve, tougher enforcement will follow.”

The fine for Betfred, one of the UK’s most established high-street bookmakers, comes at a time when the industry is under scrutiny amid a government review of the gambling laws introduced by the Labour government in 2005.

Since the review was announced there has been a rush in the industry to demonstrate improved commitment to safer gambling, while several big operators have been penalised for licence transgressions.

Earlier this month, Betway was fined more than £400,000 after its marketing material was found on the children’s section of the West Ham United website.

In August, Entain, the Ladbrokes Coral owner, was told it could lose its licence after it was fined £17m for a string of failings related to its inaction as individual customers spent hundreds of thousands of pounds.

The gambling industry has so far resisted calls from campaigners to impose strict affordability checks to prevent people spending unsustainable sums, saying controls that were too intrusive would infringe upon civil liberties.

A Betfred spokesperson said: “We will work with the UK Gambling Commission and continually review all our anti-money laundering and social responsibility policies. During our assessment, the commission found no evidence of criminal activity. We remain committed to providing a safer gambling environment for our customers.”