A motion calling for Crown Estate assets in Wales to be devolved, as they have in Scotland, has been unanimously backed by councillors in Carmarthenshire.

Doing this would enable Wales to benefit from planned offshore wind energy projects, they said, rather than the money going to the UK Treasury.

The Crown Estate manages £16 billion of land and marine resources held by the reigning monarch, according to its website, and returns all net profits – £4.1 billion over the past decade – to the Treasury.

The motion by Plaid Cymru councillors Betsan Jones and Meinir James said a poll in 2023 showed that 75% of the population of Wales backed taking control of Crown Estate assets.

“Local authorities are under huge financial pressure and placing the Crown Estate in the hands of Wales would be a significant step to address the years of lack of investment in our local Government,” it said.

Cllr Jones said the Crown Estate had £600 million of assets in Wales, owned 65% of its seabed extending out 12 nautical miles, plus the Loughor Estuary and a section of the River Towy.

She claimed the Crown Estate had responded to recent pressure by appointing a commissioner to represent Wales, and that the UK Labour Government had said that Wales would benefit from offshore energy projects. “But that does not go far enough,” she said.

Cllr James said Scotland earned more than £100 million last year from Crown Estate resources it managed after powers were devolved north in 2017.

A council legal officer said a public corporation under the control of the Scottish Government managed assets still technically owned by the monarch, and that income went to the Scottish Government.

Cllr Alun Lenny, Plaid’s cabinet member for resources, said Wales’s deputy First Minister Huw Irranca-Davies has said he wanted to work with the Labour UK Government on proposals that could devolve Crown Estate powers, and that support had also come from former Labour Secretary of State for Wales and now Lord Peter Hain.

Cllr Lenny said he hoped the Westminster Government would have responded sympathetically, but he claimed that a UK Treasury minister said it had no intention of devolving the Crown Estate to Wales.

Cllr Lenny told the Local Democracy Reporting Service he had been referring to Lord Livermore.

Independent unaffiliated councillor John James said Crown Estate benefits should come to Wales, and would enable Carmarthenshire Council to plan positively for the future. Plaid councillor Hefin Jones said Wales was a net exporter of energy. “Funds are essentially owed to us,” he said.

The UK Treasury department said Crown Estate profits were ploughed into the public purse, helping fund public services.

A spokesman said: “As part of the Crown Estate Bill, a commissioner will be responsible for giving advice about Wales to the Crown Estate board to ensure it continues working in the best interests of Wales.”

The Welsh Government said it welcomed the appointment of a commissioner, but that it was committed to Crown Estate devolution.

“We want to ensure the Crown Estate works for Wales, and officials have held initial discussions with their UK Government counterparts on the constitutional reform agenda,” said a Welsh Government spokeswoman. “These will continue to ensure we maximise the opportunities and benefits for Wales.”

The Scottish Government said taking over the management of Crown Estate resources meant decisions were are now taken in Scotland for the benefit of the country.

Examples included offshore wind leasing rounds and £50 million that had been funnelled to local authorities for coastal community benefit.

A Scottish Government spokesman said: “Crown Estate Scotland supports the delivery of ministerial priorities, particularly in terms of helping us to realise the many opportunities that exist for the growth of a fairer, greener, well-being economy and in how we respond to, mitigate and adapt to climate change.”