Pfizer will close its Little Island manufacturing plant in Cork in the latest phase of restructuring by the company of its Irish operations.

The company is moving production from Little Island to its nearby Ringaskiddy plant and says it expects to make the transition next year.

The US pharmaceutical giant has blamed falling demand for key products following the expiry of patents for the move, but the fate of the plant’s employees is unclear.

Pfizer employs 136 people at Little Island and the company said none of those would be moving to Ringaskiddy. However, a spokeswoman said the company had “a very good track record of selling on going concerns. It is a great site with a fantastic record.”

The company said none of its other Irish sites are affected by the consolidation of its active ingredient manufacturing operations.

"Pfizer has been reviewing its global manufacturing network and capacity in response to changing global demand as a result of patent expiry of a number of key medicines and the need to achieve greater efficiencies in our manufacturing," said company vice-president Paul Duffy.

He said Ireland remained a "key strategic location" for the company.

Pfizer said it will look to sell the Little Island site after the transfer in conjunction with IDA Ireland and Enterprise Ireland. The company previously successfully sold a site in Dublin to US biotech group Amgen after an earlier restructuring programme.

Pfizer employs more than 3,000 people at six locations in Ireland.