Wales must be able to participate in future European programmes if the UK government fails to reach a Brexit deal, politicians from across Europe have insisted.
Representatives from more than 20 EU regions will make the call in a declaration in Cardiff on Thursday.
First Minister Carwyn Jones said he was "not trying to undo Brexit".
But he stressed that shared interests with European counterparts "must be prioritised in the negotiations".
The meeting will be attended by political representatives from countries including Germany, France and Ireland, and Scottish counterparts, as part of the Conference for Peripheral Maritime Regions (CPMR).
The first minister will join those representatives in signing the "Cardiff Declaration", which calls on the European Commission to "open the possibility for the UK devolved administrations to participate directly in future EU programmes and co-operation" in the event of a no-deal scenario.
The declaration underlines a "strong interest" in seeing Wales continue to participate in successor programmes to Horizon 2020 (research and innovation), Erasmus+ (education and training), and Creative Europe (culture) after Brexit.
It also states that the CPMR "regrets but respects" the Brexit vote and highlights "the importance of reaching agreement on the financial obligations of the UK".
The UK government's so-called divorce bill is a current sticking point in the Brexit negotiations with the EU.
Mr Jones said: "Bringing together representatives from across the regions of Europe and signing the 'Cardiff Declaration' demonstrates our intention to collaborate with our European partners.
"Wales remains open, outward facing and international in outlook and Brexit will not change that.
"While we have been consistently clear that we are not trying to undo Brexit, we have a range of shared interests, from trade to protecting the rights of UK and EU citizens, which must be prioritised in the negotiations.
"This event and our joint declaration demonstrate that while Brexit has an impact on all European countries and regions, it must not become a stumbling block to our established strong relations that benefit us all."
Conservative Monmouth MP David Davies said it was "starting to seem as though the Welsh Labour Party is batting for the other side on Brexit".
"The people of Bridgend [Mr Jones's constituency], like the people of Wales and the UK as a whole, voted to leave the European Union and the sooner the Welsh Government can adapt to that reality the better for Welsh businesses and families alike," Mr Davies said.