The Welsh Government is warning that changes to European structural funds and the common agricultural policy could see Wales lose up to £1bn in funding between now and 2020.
With the Irish presidency currently leading negotiations on the 2014-20 EU budget, anxiety is growing in Wales at a potential loss of hundreds of millions of pounds in European funding.
Structural funding could be withdrawn from some of Europe's poorest regions, including West Wales and the Valleys.
Deputy minister for European programmes Alun Davies said that, while the EU is facing significant budget pressure, concern at proposals first floated in a budget meeting last November are creating concern. Economic challenges mean structural and CAP funding need to be sustained.
"West Wales and the Valleys remains one of the poorest regions in Europe, yet it is regions like this which would suffer most, leading to less jobs and opportunities for growth, while prosperous regions would get wealthier," he said.
Consultation is presently underway on future investment priorities in Wales.
"EU funds are critical in helping us to recover from the recession and to continue our transformation into a confident, ambitious and entrepreneurial country," said Mr Davies.