An inquiry is to be held by the Scottish Parliament into whether local authorities can afford to deliver a flagship government commitment to provide free school meals.

The investigation by Holyrood's Education Committee follows an announcement earlier this month by Fiona Hyslop, the Education Secretary, that all pupils in the first three years of primary would be given free school meals from August 2010.

The following day, however, a survey by The Herald revealed nearly half of local authorities said they could not afford to implement the policy without additional money or cuts in other areas. Now, the committee has decided to ask every local authority in Scotland what they think of the policy and whether they can afford it.

Karen Whitefield, a Labour MSP and committee convener, said: "There have been conflicting claims about whether or not local authorities have the funding in place to implement the Scottish Government's plans. The committee has agreed to write to all Scottish councils inviting them to comment."

The row over free school meals is one of the most significant blows yet to the so-called concordat - the agreement between the Scottish Government and Cosla, which represents local authorities, signed after the SNP came to power.

The concordat gave more power to councils over how they spend public money by ending the practice of ring-fencing, where money had to be used for a specific service.

There were fears that some services could lose out, and those fears were realised when the extent of the revolt over the free school meals policy became clear. The government said the cost - estimated at between £30m and £50m - would come from the settlement already agreed.

Cosla also insisted the money had already been agreed in the budget, but many councils said they would need to find additional money or face cutting other services.