British satellite provider Inmarsat said its LightSquared spectrum sharing agreement in North America boosted its revenue in the third quarter as it saw no signs of growth in its core shipping services.

The company, which provides communications to ships, aircraft and the military, reported a 18.4 percent rise in third-quarter earnings to $224.4 million, beating analysts' expectations, on 22 percent higher revenue in its global business of $245.2 million.

Chairman and Chief Executive Andrew Sukawaty said: Revenue from our Cooperation Agreement with LightSquared continues to drive strong headline growth and offset a slowdown in our MSS(maritime services) revenues.

While third quarter MSS results were in line with our expectations, as previously stated, we are unlikely to see consistent evidence of a return to MSS revenue growth until next year.

Inmarsat abandoned its forecast for 2-4 percent annual revenue growth for its core business in the summer after its shipping customers moved to lower-revenue terminals faster than it expected.

Sailors are using the broadband services to send emails and update Facebook rather than making higher revenue telephone calls.

Shares in the group plunged to a near-three-year low after the downgrade, and although they have partially recovered, stand 35 percent lower than at the start of the year.

Analysts expected the company to report third-quarter earnings of $209.5 million, according to a Thomson Reuters I/B/E/S poll.

(Reporting by Paul Sandle)