The action is the latest in a string of protests

A Unison committee approved the move, which would involve three days of action prior to an indefinite strike.

Joe Di Paola, Unison's Scottish Organiser for local government, said it was time to resolve the dispute.

However, a spokesman for the local government employers said they had not been notified about strike action.

Staff have been in dispute with local authorities body Cosla for two years.

We don't think they should be using parents and children as pawns and bargaining tools Cosla spokesman

Mr Di Paola said: "Despite days of action, and selective strikes, petitions and concentrated lobbying by Unison nursery nurses and parents, Cosla has continually failed to recognise the value of the nursery nurses' job, and the need for their grading to be tackled.

"We have been consulting with nursery nurse members across Scotland and they have told us that they feel they no longer have any alternative but to move towards all-out strike action.

"We have only moved to this stage with the utmost reluctance."

Mr Di Paola said Unison's decision to propose a ballot was designed to give Cosla an opportunity to return to the negotiating table.

Nursery nurses in Perth and Kinross, South Lanarkshire, Aberdeen, Shetland and the Highlands have resolved their disputes.

But Unison claimed there is majority support for a national pay settlement.

Minimum starting salary

A Cosla spokesman told BBC News Online Scotland that it had no idea nursery nurses were to be balloted on all-out strike action.

He said: "We are disappointed that they did not intimate this course of action to us.

"We don't think they should be using parents and children as pawns and bargaining tools. As employers we are keen to reach an agreement and would urge them to reconsider."

Cosla has argued that nurses in different local authority areas have varying pay scales and gradings, which would make such a deal unworkable.

The organisation said it has offered a pay rise of up to 12.5%, or �18,000 a year, to fully qualified nursery nurses.