Bradford could be battered by three, four and even five-day Council strikes this spring as angry workers ramp up the pressure on ministers.

Union chiefs have confirmed yesterday's one-day walk-out was just the first in a series expected to blight the summer.

Strike bosses are already talking about hitting selected services - such as waste collection and benefits - on set days in April.

And that will be followed by escalating all-out action by staff lasting for up to five days.

Patrick Kerry, Bradford Council representative of the public services union Unison, believes workers can keep public support despite the threat.

He said: "We are trying to encourage the Government to get around the table and talk to us.

"If they don't do that they will affect essential services - that is the price the Government will have to pay."

Strike action was launched after talks with the Office of the Deputy Prime Minister broke down earlier this year. Council staff oppose pension changes which will make it more difficult for them to opt for retirement at 60.

Yesterday's walk-out closed or partially closed seven of Bradford's libraries along with the mobile library service and at least 27 schools.

The action also led to a two-hour closure of Leeds-Bradford Airport, a walk-out by Police Community Support Officers and a strike by other civilian staff working with the emergency services.

An ODPM spokesman today said: "Strike action is entirely a matter for the trades unions. ODPM wants to continue holding meetings to discuss necessary reform of the local government pension scheme with all interests, including the unions.

"The retirement age of the Local Government Pension Scheme is already 65. Any retirements before that age have to be affordable from the schemes' funds.

"The difference between the LGPS and the public schemes is that this is a funded scheme which is dependent on investment income. This is why it is dealt with separately."

But Unison General Secretary Dave Prentis said: "Our members have taken the decision to strike very seriously indeed. They are not selfish people, they are not using any excuse to call 'strike' and have a day off - they are asking simply for what they have paid for and what they deserve."