The European Union's financial watchdog says rules introduced more than a decade ago to tackle illegal logging have not been fully enforced, allowing suspect timber to still enter the EU.
The European Court of Auditors said in Thursday's report that Greece, Hungary, Romania and Spain had not implemented measures in an EU plan from 2003.
Auditor Karel Pinxten said "illegal timber could still be imported into the EU via these four countries."
The court criticized the EU's executive Commission for failing to correctly monitor the plan, part of which was meant to encourage non-EU countries to crack down on the black-market timber trade.
It said the Commission failed to properly manage the use of financial support worth 300 million euros ($339 million) to 35 countries for 2003-2013.