The £2.99bn purchase of the Lucas brand owner TRW Automotive by New York equity house Blackstone Group is likely to be delayed after the main part of a purchase “chain” deal hit the regulatory buffers.

US Department of Justice officials have put conditions on the proposed purchase of TRW's defence business by rival Northrop Grumman.

With the purchase of TRW, Northrop had hoped to sell off TRW's automotive parts business to Blackstone in order to concentrate on its core defence business. Northrop had planned to retain a small shareholding in TRW Automotive.

According to today's Financial Times, Northrop says it hopes to complete the deal next Wednesday when its shareholders vote.

The delay centres on safeguards to ensure Northrop doesn't block access to some of TRW's technologies to rivals – used in building classified military satellites.

As well as the Blackstone purchase of the auto parts business, the purchase by Goodrich of TRW's aircraft parts division is also hanging on the Northrop TRW defence purchase deal going through.