UPDATE 1-Trafficmaster buys Tri-Mex, H1 trading in line

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LONDON, July 22 (Reuters) - British driving services firm Trafficmaster Plc (TFC.L: Quote, Profile, Research) has agreed to acquire vehicle tracking company Tri-Mex Group for up to 4.75 million pounds ($9.49 million) and said half-year profits would be in line with its expectations.

Trafficmaster said the Tri-Mex acquisition would be paid for over three years from April 2009 on a sliding scale -- dependent on growth -- with a maximum total payment of 4.75 million pounds.

Tri-Mex operates "Eurowatch", a pan-European service for stolen vehicle and cargo tracking with clients Jaguar and Land Rover.

Trafficmaster also said half-year revenues in the UK and the US have increased on the same period last year with first-half profits likely to be in line with market expectations.

In the first-half last year Trafficmaster delivered gross profit of 14.1 million pounds on sales of 23.7 million.

The company said its Business and Consumer Services divisions had performed well during the period, with UK Traffic Information showing continued growth. (Reporting by Rhys Jones; editing by Sue Thomas)