Satellite operator Inmarsat pushed up profits yesterday as its first results as a listed company benefited from strong demand among maritime users.

The group, which has ten satellites providing voice and data services, revealed a four per cent rise in first-half revenues to $ 253.6 million (£140.8 million) with underlying earnings ahead 11 per cent at $ 171 . 8 million (£95.4 million).

Inmarsat said the maritime sector had been the main driver of its improvement with growth in data revenues more than offsetting ongoing decline in voice.

On land, revenues were lower despite increased usage following the tsunami in Asia, while the aeronautical sector continued to expand as a result of greater use of its Swift64 service, which targets government and business jets.

Inmarsat added its growth prospects remained strong following the commercial launch of the first of its broadband-enabled Inmarsat-4 satellites in May.

It is in operation above the Indian Ocean and has enabled the company to migrate regional customers of its broadband network onto the satellite, meaning it no longer has to make lease payments to another operator.

Controlled from Inmarsat's London offices, the satellite was mainly built in the UK through manufacturer Astrium's sites at Portsmouth and Stevenage.

It is the size of a doubledecker bus and 60 times more powerful than its predecessors.

With two more satellites due to be launched from the end of this year, the I-4 programme is on track to meet its budget of $ 1.5 billion (£833.1 million).

Inmarsat made its debut on the London market in June.