Cardiff airport handles 1.5m passengers a year

The group, which has its UK head office in Watford, employs around 7,000 people in the UK on a range of projects including a Cardiff-based PFI deal and a contract to maintain the bridges on the River Severn.

However, it does not have a presence in the UK airport sector, despite having interests in airports around the world.

In a separate, but related development, the Financial Services Authority is considering examining the share dealings of two of TBI's non-executive directors.

Both substantially increased their holdings in the company less than a fortnight after it rejected Vinci's first bid.

TBI are Britain's second biggest airport operator and a business that retains strong Welsh connections.

Chairman Stan Thomas is the brother of Cardiff rugby club owner Peter - and one of Wales's richest men.

Cardiff International Airport handles around 1.5m passengers a year and claims to be one of the UK's most successful regional airports.

Global network

Since acquiring the airport in the mid nineties TBI has developed a global network of interests that stretches from Scandavia to south America.

But in the past few weeks the company shares have slumped after the withdrawal of BMI British Midland services from Belfast International Airport.

This latest offer represents a premium of just 6% to the firm's closing share price on 1 August, before BMI British Midland's "surprising" decision to withdraw Heathrow and East Midlands services from Belfast International, part of the TBI portfolio.

TBI has advised its shareholders not to act until it has made a decision.

Sources said Vinci had made two previous approaches to TBI, the first before the collapse in the firm's shares, but gained a brusque response.

A takeover might come as a disappointment to TBI directors, who have since 1995 overseen the firm's transformation from a property company into a specialist airports operator with stakes in 26 sites, principally in the UK, US and Bolivia.

Besides Cardiff International the TBI portfolio includes Belfast International and Stockholm Skavsta airports, and a controlling interest in London Luton airport, home of budget carrier EasyJet.

TBI reported underlying pre-tax profits of �19.3m for year ended March, up 6% on the year before.

French giant

For Vinci, a successful takeover would represent a further success in a drive to promote its independence as a construction and services group.

The firm was in February 2000 spun off from Vivendi, which has focused on its media and leisure interests, and merged with Canada's Seagram, owner of Universal Studios.

Vinci a year ago merged with French rival GTM to form a group with turnover of 17.3bn euros last year, and a market capitalisation of 5.78bn euros.