The UK Government should use this autumn’s Spending Review to "share responsibility and allocate long-term funding" to make Cymru's coal tips safe, Finance and Local Government Minister Rebecca Evans has said.
The Welsh Government said that as Cymru's climate changes, coal spoil tips need "attention and long-term funding to prevent the risk of future landslips".
Based on information from the Coal Authority, the Welsh Government has estimated that more than 40 per cent of all the UK’s coal tips are located in Cymru and around one in seven of these are classed as high risk.
Finance and Local Government Minister Rebecca Evans will call on the Chancellor of the Exchequer Rishi Sunak to share responsibility and allocate funding to deal with the pre-devolution legacy of coal mining in Cymru.
It is estimated at least £500m to £600m will be needed over the next 10 to 15 years.
The Minister said: “Wales is disproportionately affected by the legacy of coal mining, and climate impacts are increasing the risks disused coal tips pose to our communities. As a pre-devolution issue, we need the UK Government to share responsibility and prevent another landslip from happening.
“As rainfall intensifies and temperatures rise, the risk to life and livelihoods is increasing unpredictably.
“The UK Government has a legal and moral responsibility to work with the Welsh Government to address this issue and fund these long-term costs.
“There is an opportunity for us to work together in the coming years to tackle the climate and nature crisis we face and this year’s Spending Review is the chance to find that common ground and to leave a positive, fairer and lasting legacy for former mining areas in Wales.”