Union Anger as Royal Mail Plan to Hire 30,000 Temps During Strike

But it said the extra workers would cut the impact of "unjustified and irresponsible" industrial action.

Employing extra people to do the work of staff who are on strike is illegal under employment law.

Royal Mail said the recruitment drive was not about bringing in workers to do the work of striking staff, but to ensure there were enough staff to clear any backlogs as well as tackle the seasonal increase in mail volume.

Liberal Democrat leader Nick Clegg told the BBC: "I think Royal Mail are right to try to keep mail flowing and the postal service going."

"I think the people who are calling for a strike are wrong, which isn't to say they don't have legitimate concerns. But taking the whole country hostage like this is the wrong thing to do."

Why are the strikes taking place?

At the heart of the latest dispute is the deal that the two sides signed to end the last national strike, the 2007 Pay and Modernisation Agreement.

The CWU says that Royal Mail has carried out three of the four planned phases of that agreement with full and frank dialogue. It claims the company is refusing to talk to it about the final phase, how the roll-out of its modernisation plans would affect job security.

One aspect of this modernisation involves the walk sequencing machine, a device which organises letters into the order the postmen and women will deliver them the next morning. The CWU fears the national roll-out of this machine will mean thousands of full-time jobs will go and that there will be a massive increase in the number of part-time workers.

The CWU argues that even though it agreed in 2007 that jobs would need to be lost as part of the plan, specific details about the actual nature of the modernisations were unknown at that time. It claims that when Royal Mail stopped talking to staff or the unions about the long-term effects on job security, it had no choice but to threaten a strike in order to get discussions moving again.

Royal Mail argues that it did not stop talking to the union about the future strategy of the business and says it will continue to involve the CWU in developing plans.

It insists that where local staffing level changes are concerned, it has agreed that proposals should be transparent and that it has been discussing with the union how it can give people more confidence in this area.

Why is Royal Mail making the changes?

Royal Mail says the number of letters and parcels its core business delivers are falling by 10% each year, losing it £170m a year.

To respond to this decline in business, it says staffing cuts are inevitable.

In 2008, the Royal Mail Group went into the black for the first time in 20 years and profit at the main letters and packages unit was £58m from a turnover of £6.7bn.

Royal Mail says this margin is very small considering the size of the turnover. The group also has a £6.8bn pensions deficit.