European Union states have rejected a set of rules governing which financial products can be called “green” and “sustainable”, an EU official said, in a major setback for the bloc’s climate ambitions.

The decision overturned a deal struck just last week by EU lawmakers and the Finnish presidency of the EU, which negotiators hailed as a landmark compromise that could establish a global standard on green bonds and other financial products aimed at climate-conscious investors.

Britain, France, the Czech Republic, Hungary, Poland, Slovakia, Romania, Bulgaria and Slovenia opposed the deal at a meeting of EU diplomats in Brussels, fearing it would prevent investments in nuclear and coal projects from being labelled as green, according to Reuters.

Such investments were not explicitly excluded from the EU’s new classifications, known as taxonomy, but under the rules it would be very difficult to label them as green, potentially reducing future funding for those industries.

France relies on nuclear energy, while European countries are still largely dependent on coal.