Biotech company Horizon Therapeutics has submitted a planning application to expand its development and manufacturing facility in Waterford, which it said will create a further 350 jobs over time.

Horizon said the expanded facility would allow it to add new drug substance biologics development and manufacturing capabilities.

The planned facility would expand Horizon's footprint, adding about 320,000 square feet to its current 44,000 square foot drug product biologics facility.

Horizon said it will provide additional details with respect to potential investment and timeline as the planning application process proceeds.

Horizon purchased its existing facility in June of last year for $65m with the understanding that adjacent IDA Ireland land was available for further manufacturing and development expansion.

"As we grow as a global biotechnology company, it is important to continue to invest in our development and manufacturing capabilities to supplement our current network of contract manufacturing organisations to maintain flexibility over our production and supply," said Tim Walbert, chairman, president and chief executive officer of Horizon.

"The planned expansion to add this drug substance facility is important to the long-term growth of our commercial and pipeline biologics as well as our commitment to Ireland," Mr Walbert said.

Horizon Therapeutics has had its global headquarters in Dublin since 2014, but the Waterford site was the company's first move directly into manufacturing.

As well as its role as global headquarters, Horizon's Irish operations include several key functions such as technical operations, finance, legal and R&D.