PARIS — The European Union's top court ruled Thursday that EU authorities unfairly froze assets of a Saudi businessman who was accused of financing al-Qaida, by failing to explain why he was targeted.

The European Court of Justice upheld a lower European court ruling in the case of Yassin Kadi, rejecting an appeal by EU and British authorities.

After the Sept. 11 attacks, Kadi's charitable Muwafaq foundation was identified by the U.S. Treasury Department as an al-Qaida front and placed on a terror list in October 2001. The United States, the EU, Switzerland and Turkey all took action against Kadi, following a U.N. anti-terror order obliging U.N. member states to freeze assets of people and entities suspected of funding terror groups.

Kadi denied financing terrorism, and said his foundation closed before the Sept. 11 attacks. He has fought legal battles for years against the asset freezes, and was removed last year from the U.N. blacklist of people under sanctions for suspected al-Qaida funding.

In 2008, the European General Court ruled that putting Kadi's name on the terrorist list infringed some of his rights under EU law, such as his right to defense and judicial protection.

EU and British authorities appealed that ruling.

In Thursday's announcement, the European Court of Justice sided with the lower court, and argued that suspects need to be informed of why they are being listed and have a chance to contest it.

"The Court holds that, since no information or evidence has been produced to substantiate the allegations, roundly refuted by Mr. Kadi, of his being involved in activities linked to international terrorism, those allegations are not such as to justify the adoption, at European Union level, of restrictive measures against him," the court said in a statement.

Authorities, however, sometimes want to keep information about a terrorist suspect confidential for security reasons. The court said that in such cases, it is up to EU courts to assess whether and when it's appropriate to withhold that information from the suspect.