Qinetiq, the UK defence technology group, is in talks to buy a privately held company that provides top-level advice to US intelligence services, in a move that will give it access to the heart of the lucrative US defence market.

The company is expected to confirm early this week that it is buying Dominion Technology Resources (DTRI) for about $100m. DTRI provides a range of consulting services and technology expertise to a number of government intelligence services and other classified customers.