Image caption Swansea council leader Rob Stewart: "I can't spend money I simply have had taken away"

Cuts to local authorities' education budgets are "impossible to defend", the leader of Swansea council has said.

In a letter to Education Secretary Kirsty Williams, Rob Stewart criticised cuts to a grant that was partly used to fund teaching children who do not speak English as a first language.

The Labour councillor said the money had been taken away but councils were still expected to provide the service.

The Welsh Government said talks to provide extra funding were under way.

In the last budget, the Welsh Government responded to calls from local authorities to cut the number of grants that force them to spend money on specific services and said it would instead transfer the money into the main funding pot.

But Mr Stewart said his education budget would face a shortfall of £2m in the next financial year.

Image caption Kirsty Williams is the sole Liberal Democrat in an otherwise all-Labour cabinet

He said an 11% cut to the Education Improvement Grant for Schools had not been fully handed back to main funding pot.

The council would now have to fund teaching support for children from ethnic minorities from existing budgets, he said.

Cardiff council also said it faced a financial shortfall in its education budget.

In a letter to council leaders in November, Liberal Democrat AM Ms Williams said she still expected £10m to be spent across Wales to support ethnic minority learners.

Mr Stewart responded to her, saying the budget for the next financial year had been "disingenuously packaged".

He wrote: "You have placed yourself in a tautologically impossible to defend position. You have proposed a cut to a specific grant which previously, amongst others, funded Gypsy, traveller and minority ethnic groups.

"You have made no cash transfer to revenue support grant, unlike ministerial colleagues.

"You tell us how to prioritise spending - including demanding we spend the same amount on a function for which you have unequivocally removed the grant - with no recompense in cash in the revenue support grant.

"I can't spend money I simply have had taken away."

The Welsh Conservatives have lodged a request in the Senedd for an urgent question on the matter .

Tory AM Darren Millar said: "The Welsh Labour-led Government needs to explain why, in wielding cuts to this specific grant, they have made no additional transfer to the main budgetary pot, as was previously promised."

Analysis by Nick Servini, BBC Wales political editor

Kirsty Williams, as the solitary Liberal Democrat in the Welsh Government cabinet, has navigated her way through the choppy waters of dealing with Labour council leaders successfully since taking on the job 18 months ago.

The response from Rob Stewart is the exception, rather than the norm.

A source close to Ms Williams says the tone of this strongly-worded letter caught her team by surprise and has not been helpful to the discussions behind the scenes - code for anger at the way the council leader has responded.

The Welsh Government defence is that it is doing what councils want in freeing them up from specific grants, but at a time when there is not much money sloshing around local authority coffers, there are inevitably going to be disagreements about whether the councils are being left out of pocket.