Figures from 200 parties in 25 countries suggest hardline groups have had rise in donations in recent years, increasing war chests before European parliament elections

A quarter of all private money donated to political parties in the EU is going to far-right, far-left and populist movements, boosting their finances by millions of euros before crucial European parliament elections next week.

With the polls predicting a rise in support for hardline conservative, Eurosceptic and pro-Russia parties, the Guardian and other 26 media partners, led by the investigations group Follow the Money, are publishing Transparency Gap, the most extensive analysis yet of political financing in the EU.

The data was gathered from the annual reports of more than 200 parties across 25 countries.

It shows €150m (£128m), the equivalent of €1 in every €4 of all private donations made between 2019 and 2022, went to populist parties and those with the most extreme political views.

Far-right groups have pulled in more than €97m, equivalent to €1 in every €7 of private money.