More than 17,000 engineers, maintenance workers and signallers at Network Rail protesting against bosses' demands for massive job cuts will shut down Britain's railways for a week after Easter Monday in the first national rail strike for 16 years.

Almost a thousand Network Rail supervisors will also join the strike, which begins at 6am on April 6 - the day that Mr Brown is expected to announce the general election - and is set to continue for four days.

Network Rail want to axe 1,500 maintenance posts, increase for already overworked signallers, renege on agreements and impose changes that will clearly undermine safety. Even the government's own rail watchdog the Office of Rail Regulation agrees that Network Rail's proposed changes pose a threat to safety.

Network Rail operations director Robin Gisby tried to dismiss the unions' concerns and threatened to use managers to scab on the strike.