The jobs will be divided between two locations; 250 jobs will be based in the company's Craigavon headquarters and the remainder will be located in Larne.

The expansion by the Craigavon based company is being backed by the Industrial Development Board which contributed £10m, 25% of the total cost of the development.

The development has been described by Northern Ireland Secretary of State Peter Mandelson as a strategic investment by a world class company.

Announcing the investment, Mr Mandelson hinted at the economic benefits of political stability.

"For companies like Galen to make the most of the huge potential Northern Ireland has to offer, we need a permanent settlement, we need an unbreakable peace," he said.

Further expansion plans

Galen was set up by Dr Allen McClay 30 years ago - it now has sales of £50m and 1100 employees.

Dr McClay suggested that the company has plans for further expansions, not necessarily in Northern Ireland.

"You can't stay in an insular state if you're going to be a global company," he said.