The Communication Workers Union will seek an injunction against the use of 30,000 temporary workers as "strike breakers".

The Statesman online reports that the CWU will go the High Court on Friday in hope of getting an injunction against Royal Mail's use of agency staff to undermine the postal strike.

The union argues that the company's use of 30,000 agency workers to clear the backlog of mail caused by the strike is unlawful.

Royal Mail commented that its use of temporary staff was "entirely in line with all employment law".

CWU members are due to hold two further rounds of strikes on Friday and next Monday in the hope of reaching an agreement before Christmas.

Royal Mail now claim the number of letters held up as a result of the latest strikes has fallen from 50m at the weekend to 25m.