An “unrealistic” plan to staff libraries with volunteers has come under fire.

One-day-a-week closures were planned at West Barnes and Colliers Wood libraries from April because of budget cuts - but on Tuesday Merton Council said they would be postponed to allow time for volunteers to step into the breach.

This week a community group and opposition councillors criticised the announcement.

The closure of West Barnes library on Mondays and Donald Hope library in Colliers Wood on Fridays was announced earlier this year, in a bid to save £81,000.

But cabinet member for communities Martin Whelton has revealed the closure will now be postponed until the beginning of July, in the hope newly-formed friends groups will come forward and offer to run the libraries on days the council could not afford to.

Councillor Whelton said he did not know how many volunteers would be needed to beat the closures, but interest had already been show at public meetings about the future of the libraries.

He said the initiative was a test of David Cameron’s big society project, which aims to encourage volunteering.

He added: “We think this is the best way forward.”

Keith Spears, chairman of the Colliers Wood Residents Association, said: “I think it’s unrealistic. I see volunteers as supplementing paid staff, not replacing them. It’s not just a matter of principle but of practicalities.”

Mr Spears said plans to form a friends group for Donald Hope library were going well, with dozens of people interesting in joining.

But he warned volunteers should not be expected to do the same job as paid staff, and would struggle to deal with difficult or agressive users.

Liberal Democrat and West Barnes councillor Iain Dysart said he could not welcome the announcement as it was “a stay of execution not a reprieve”.

He said the community should be encouraged play a part in the running of the library.

But he warned: “There are limitations – volunteers shouldn’t be expected to carry out the work of professional, trained librarians.”