British engineering group GKN on Monday rejected an improved and final takeover bid, worth £8.1 billion, from turnaround specialist Melrose Industries.

Melrose had earlier Monday offered the equivalent of $11.2 billion or 9.1 billion euros -- in response to GKN's announcement ahead of the weekend that it had agreed a tie-up of its automotive unit with US car parts group Dana.

GKN's move on Friday had been seen as a defence against a full takeover by Melrose, which had already had an offer worth £7.4 billion turned down. Responding to Monday's higher offer, the board of GKN described it "as entirely opportunistic and believes that its terms fundamentally undervalue" the company and its prospects.