Schools and rubbish collections could be plunged into chaos as thousands of city council workers threaten to strike over pensions.

Union officials today warned of "massive disruption" in Brighton and Hove if their members decided to walk out.

More than 3,000 employees belonging to Unison, the biggest trade union in the city, are being balloted over strike action next Monday.

Alex Knutsen, secretary of Brighton and Hove Unison, said: "It is not just Unison members who are being balloted over this.

"It is members of the GMB, the Transport and General Worker's Union, Amicus and other public sector unions.

"If they vote for strike action, which I'm confident they will, it will be the biggest strike since 1926. We will have 2.4 million people on strike across the country.

"Initially, it will be one day of strike action to show the strength of feeling. But if that doesn't have any effect, we will move swiftly on to more days and we could have a three-day walk-out.

"Any walk-out would lead to people's household rubbish being left uncollected and pickets outside schools. That would definitely happen. It would have an immediate effect on everybody in the city."

Mr Knutsen said half the city's schools had to close last January when teaching assistants represented by the GMB andUnison went on strike.

He said a strike involving council employees in all departments would be devastating.

Unions want the Local Government Association (LGA) to drop planned changes to the pension system which would mean people taking early retirement would no longer automatically get a full pension.

Councillor Paul Elgood, leader of the council's Liberal Democrat group, said the prospect of so many staff walking out was extremely worrying.

He said: "We could see the city grind to a halt under this action. The staff that Unison represents are very much at the front line of the council's work and any strike would have a severe effect on the provision of services.

"I am sure they would think long and hard before making the decision to go on strike."

Councillor Sue John, the council's acting leader, said: "Negotiations between the unions and the LGA are still continuing and I'm still hopeful there will be a positive outcome."

Staff being balloted worked in various departments including housing, social services, the fire service, education, probation and environmental health.