Last week, GlaxoSmithKline announced that a review of the Montrose factory's operations as part of a £1.5billion global restructuring programme, and that a number of staff could face redundancy as a result.

But rumours that staff made redundant before the factory was saved from closure in 2006 and subsequently rehired on permanent contracts would not be compensated for possible redundancy have been dismissed.

However, the pharmaceutical giant admitted that those members of staff hired on a "contingency" basis - some 83 members of the 386-strong workforce – will be paid off without the benefit of a redundancy package, either when their contracts expire or if the review finds their positions are not sustainable.

A spokesman for GSK said: "They are what GSK calls contingency workers, agency and part time staff, hired to meet peaks of demand in products.

"Essentially, what could happen is that contingency workers can come and go as per the terms of their contracts.

"Some of those may have been made redundant previously and may have come back to the site, but not many of them.

"But GSK are not making redundancies at the moment. That may be a consideration of the review."

The spokeperson added that a significant portion of the contingency staff were brought in only to work on the two-year £35million upgrading and refurbishment on the site, and were likely to have been on a mix of fixed term and indefinite contracts on the understanding that their positions weren't permanent.

But he stressed that any decision on whether or not there would be any redundancies would not be made until the review is completed in approximately three weeks time.

GSK last week said that closure or sale of the Montrose site was not being considered as part of the review.