The alliance of centrist political parties in the European parliament faces a corporate funding controversy in France that threatens its tie-up with French President Emmanuel Macron's new party.
Investigations by Le Monde and France 2 earlier this week showed that the Alliance of Liberals and Democrats for Europe group (ALDE) had accepted 425,000 euros ($ 480,000) since 2014 from major companies including Google, Microsoft, and Bayer to pay for its annual conferences.
Although such sponsorship is allowed at the EU level, it is illegal in France and many other European countries.
Macron issued a law in 2017 aimed at improving transparency in the French political system and reducing the influencing of outside interests.
"None of our European lawmakers will join a political party or grouping during the next parliament which tolerates financing like this," Stephane Sejourne, campaign director for Macron's Republic on the Move (REM), warned on Tuesday.
The group, which is the fourth largest in parliament with 68 seats, said it would stop taking such donations in the future "to avoid all confusion."
Martin Le Pen, the far-right leader in France, focused attention on ALDE's corporate fundraising last week, highlighting how the grouping had taken money from the US seed company Monsanto, which is now part of German chemicals group Bayer.
Monsanto, which is regularly targeted by environmental activists in France, has lobbied EU lawmakers and the executive arm intensively in the previous years to try to prevent a ban on its controversial weedkiller Roundup.