Around 120 staff at the airport walked out at 1900 GMT on Monday.

Last-minute talks failed to resolve the dispute in time to avert strike action.

Management put a new pay offer on the table which is due to be voted on Wednesday.

Members of the GMB union voted in favour of a series of walkouts, in protest at plans to cut their pay by 40%.

It is the first of three five-day strikes and is due to end on Friday morning.

Passengers are being advised to check in as normal, as extra staff have been brought in to provide cover.

Wage cut 'unacceptable'

The airport says it needs to cut costs to remain competitive.

The workers' union, the GMB, says it is unacceptable that a quarter of staff are being asked to accept a 40% wage cut.

Management says the money it saves by cutting the salaries of some workers will enable it to take on 30 more staff.

The savings will also allow it to give other employees a wage increase, the airport claims.

The conciliation service Acas is involved in the last-minute talks.