Pharma giant Eli Lilly is to double the amount it is investing in a new biologics manufacturing facility in Limerick to $1 billion.

The company announced the $500m investment and the creation of 300 new jobs in January of last year.

Today it said that it would increase the amount of money it is putting into the plant and as a result 1,200 temporary construction jobs would now be created, up from a previous estimate of 500.

The integrated manufacturing plant will be used to produce biologic ingredients for use in a range of therapies developed by the company.

In October the planned development received planning permission from the local authority.

The proposed plant will be built on a greenfield site at the IDA's Raheen Business and Technology Park.

The Limerick campus will include plans for a significant solar energy investment which it is estimated will produce 3.17 million kWh of renewable solar energy per year, enough to power 755 homes.

It will also include rainwater harvesting for re-use within the site, resulting in a saving of roughly 2 million litres of water per annum.

Once in production it will require workers with a range of specialities, including engineers, scientists and operations personnel.

Lilly has had a presence in Ireland since 1978 Lilly and employs almost 2,700 people at its two sites at Kinsale and Little Island, County Cork.

''Eli Lilly has had a presence in Ireland for over 40 years and this significant investment, adding further biologics drug substance manufacturing to its already substantial Irish operations and jobs, underscores the strategic importance of Ireland in Eli Lilly’s global operations," said Interim IDA chief executive, Mary Buckley.

"It is proof of the company’s future commitment to Ireland and testament to Ireland’s continued attractiveness as a location for investment.’’

The news was also welcomed by the Minister for Enterprise, Simon Coveney.

"The news demonstrates their commitment to Ireland and highlights the wealth of talent we have to offer," he said.