Saracens and Bath are being investigated by Premier Rugby for alleged breaches of the controversial salary cap system which could see them hit with hefty points deductions and fines.

Sportsmail has learned an inquiry is under way following ‘whistleblower’ testimony. It appears to substantiate allegations that clubs are flouting rules aimed at maintaining financial stability among top-flight teams.

Saracens, backed by a consortium of South African-based businesses, mounted a pre-emptive public relations campaign calling for the abolition of the £5.5million annual cap. They claim it is ‘outdated’ and ‘possibly illegal’.

Saracens are facing heavy fines and point deductions over alleged breaches of salary cap regulations

But it has emerged a whistleblower — understood to be a disgruntled player’s agent — has complained to Premier Rugby’s recently appointed salary-cap auditors about the way Saracens structure payments to overseas players.

Under scrutiny is how Saracens’ South African players are recompensed, with allegations that payments are routinely made into offshore accounts to avoid the cap.

‘Saracens have been backed into a corner and that’s why they’ve come out and said what they’ve said at this particular time,’ said one source. ‘A whistleblower has dished the dirt. It could be messy.’

The investigation into Saracens is also understood to focus on the deal to bring the former Scotland lock Jim Hamilton to Allianz Park.

Bath have also drawn attention to themselves after a number of large offers made to recent targets

Bath have drawn attention because of a number of recent big-money offers made to transfer targets, including Wales and Scarlets fly-half Rhys Priestland and South Africa back-row star Duane Vermeulen.

The recommended sanctions for breaches of the cap are severe. Clubs found guilty of exceeding it by £75,000 face a four-point deduction, but that figures rises to a maximum of 40 points for a breach of more than £250,000.

There are possible fines of £3 for every £1 over the cap, rising to £10 per £1 for a third offence, which could see a club incur a potentially crippling £2.5m fine for breaches of over £250,000.

The scale of the alleged breaches is yet to be established.

Saracens chief executive Edward Griffiths said the cap had to go for English teams to compete in Europe

A Premiership Rugby spokesman said: ‘Premiership Rugby cannot comment on whether investigation proceedings are taking place or not. Any such investigation would be done under the salary capping regulations 2013-14.’

Saracens indicated they have the backing of six other Aviva Premiership clubs — although a Sportsmail investigation failed to find significant support. Saracens, widely viewed as a commercial pioneer for English professional rugby, have long since objected to the salary cap.

The London club believe the cap is a restraint of trade. They say it hampers clubs’ ability to compete with rich French giants like Toulon and Racing Metro — who this week signed All Black Dan Carter on a deal worth around £800,000 per season.

Jonny Wilkinson lifts the Heineken Cup trophy for Toulon, who defeated Saracens 23-6 in the final

Bath have received huge financial backing from their new millionaire owner Bruce Craig in recent seasons.

‘The salary cap has served its purpose,’ said Saracens chief executive Edward Griffiths.

‘It would be a pity if the world’s top players light up the World Cup on English soil and then leave to play club rugby in France.

'If the salary cap is left to forbid the required investment, it will kill any hope of growth.’

A Premier Rugby statement read: ‘The salary cap ensures the financial viability of the member clubs and underpins the sustainable growth of the competition for all stakeholders.

‘In addition, the salary cap provides a level playing field for all clubs, ensures a competitive Aviva Premiership Rugby competition, promotes homegrown players and supports the performance of the England team.

‘It allows the recruitment of elite players from other countries through the excluded players provision.’

Saracens’ claim that they have significant support appeared unfounded.

Dan Carter, who has just agreed to sign for Racing Metro, chose France over the Aviva Premiership

Exeter chief executive Tony Rowe said: ‘We believe at Exeter that the salary cap should be higher than it is but we don’t think it should be abolished. We’d support it being raised to around £7.5-£8m to put us on a par with a lot of the French clubs.’

Leicester, whose 24,000-capacity Welford Road stadium and large fan-base sees them generate the highest revenues from ticket sales in the Premiership, also appear to be against an abolition.

A club insider said: ‘The club is already stretched to the maximum by paying up to the salary cap. There’s no appetite to abolish the cap. It would be disastrous for Tigers.’

Harlequins distanced themselves from Saracens while Wasps are understood to have told Premier Rugby they have no interest in scrapping the cap.