UK security firm Securicor has seen profits rise 13% in the six months to March, despite problems at its US aviation arm following 11 September.

Argenbright, its stand-alone US airport security firm, reported a net loss of £13.1m, compared to a £10m profit for the same period last year.

The US unit suffered from a decision to turn over airport security to the government following the attacks on New York and Washington.

Despite this, overall group profits were up to £30.3m, from £26.8m for the same period last year.

Securicor said it believed Argenbright was free of any liability arising from the terror attacks in the US.