Twickenham is investigating the South African company running Saracens, South African Investments Limited, believing it may breach International Rugby Board regulations on the ownership of clubs.

SAIL has a 50% stake in Premier Team Holdings, the company that runs Saracens. It also has a 50% share in the Blue Bulls Company Ltd, a South African Super 14 franchise, as well as 24.9% of the shares in Western Province Rugby Ltd.

The IRB is meeting in Dubai this week, where the World Sevens are being held, and Rugby Football Union officials will seek a ruling on the board's regulation 14 which states: "No individual, body corporate, partnership, trust or any other entity may directly or indirectly own or control more than one club except with the prior written consent of the Union concerned, or where clubs from different unions are involved, the written consent of the unions concerned and the Board."

The RFU has not given its permission for SAIL to have a stake in Saracens and the governing body is concerned that the Watford-based club will be turned into a South African satellite. Eighteen players were last week told their contracts would be terminated at the end of the season, and the England captain, Steve Borthwick, is said to be considering his future because of the upheaval.

The former South Africa international, Brendan Venter, will take over from Eddie Jones as head coach during the summer. At least three current Springboks have been approached and the RFU and Premier Rugby are concerned that the club will employ few players who are eligible to play for England with Venter saying he wants to create a rugby home for South Africans in England.

Gloucester's owner, Tom Walkinshaw, has resigned as chairman of Premier Rugby after eight years. He has been replaced by Leicester's chairman, Peter Tom. Walkinshaw helped negotiate the eight-year agreement between the clubs and the RFU over the management of elite players.