Staff at the Bristol office of regional contractor Stradform are said to be concerned for their jobs amid speculation that Vinci is poised to buy it.

Vinci is understood to be carrying out due diligence on the £45m-turnover Cardiff company, and the 30 staff are reportedly worried about its overlap with Norwest Holst, a Vinci subsidiary that has 45 staff in Bristol.

One source close to the deal said: “Stradform is strong in south Wales and this deal only makes sense for Vinci if it is looking to push into that region. It is already strong in Bristol.

“The real fear is that Bristol will close if the deal happens because of the doubling up of ops and commercial managers.”

It is not known how much Vinci is willing to pay but one industry expert put the price tag at about £7m. It is understood that delegations from France have paid several visits to Stradform’s Cardiff office.

Stradform, which has offices in Cardiff, Bristol, Birmingham and Reading in Berkshire, is part of the £68m Fifehead Group.

Ken Haines, Fifehead’s chairman, refused to comment on the speculation over Vinci but said: ”We always treat approaches with the seriousness they deserve.”