The car components business formerly owned by LucasVarity could be back on the auction block in the fallout from a US takeover battle.

TRW, the buyer of LucasVarity in 1999, yesterday received a $5.9bn (£4bn) takeover bid from the Los Angeles defence company Northrop Grumman. The aim is to keep hold of the defence and aerospace interests of TRW and divest the automotive division - despite car parts accounting for 60% of TRW revenues.

TRW employs around 6,000 people at factories throughout Britain, including 600 at Wednesbury in the West Midlands which supplies Ford and Nissan. It also employs 635 people in Tyne and Wear, 1,300 in West Glamorgan and has other plants in Birmingham and Aylesbury.

The company employs another 4,000 aerospace workers who would probably be retained by Northrop if the bid were successful.

Cleveland-based TRW dismissed the bid as opportunistic. It comes two days after the share price took a bruising on the resignation of chief executive David Cote to join Honeywell International.

In a statement, TRW said the company "finds it regrettable that Northrop Grumman has chosen to make this proposal immediately following the unexpected departure of its chief executive and the aberrationally low stock price that resulted."

The all-paper Northrop offer values TRW at $47 a share, an 18% premium to the closing price on Thursday. Wall Street bet on the offer moving higher - TRW shares were changing hands at $50 by midday.

LucasVarity was formed from a 1996 merger be tween Varity in the US and Lucas Industries in Britain. During 2001, the acquisitive Northrop spent $7.1bn in two deals that made it the world's largest builder of warships. Also maker of the Global Hawk pilotless spy plane recently deployed in Afghanistan, Northrop has an $18bn capitalisation.