Engineering group Costain has confirmed that it has had a takeover proposal rejected by outsourcing company Mouchel.
Costain said it contacted Mouchel's board on 2 December, only for its approach to be turned down on 6 December.
Mouchel had already said it had received a preliminary takeover offer, but did not name the interested party.
Costain said it was now uncertain whether it would make a formal bid.
When Mouchel made its announcement on 6 December, its shares ended that day's trading up 28%.
Prior to that they had fallen by 80% so far this year, as a result of the UK government and local authorities reducing spending on the new infrastructure development that the company provides.
Costain said it had proposed making an all-share offer for Mouchel at a 87% premium to Mouchel's closing share price on 3 December.
David Allvey, Costain's chairman, said: "The board of Costain believes that there is a compelling strategic rationale for combining Costain and Mouchel."
Mouchel was founded in south Wales in 1897 by Frenchman Louis Mouchel. Today it has its headquarters in Woking.
Some of its earliest contracts included helping to build London's Earls Court Exhibition Centre and stands at Manchester City's former Maine Road stadium.
Mouchel's current operations include half-ownership of Enterprise Mouchel, which has a contract to grit roads in south London.
Costain was established in Liverpool in 1865, but is now based in Maidenhead. It was involved in building the Channel Tunnel and the Thames Barrier.