The headquarters of champions Olympique Lyon and Bastia were searched by French police on Thursday as part of an investigation into the finances of a leading Corsican nationalist.

The police, including inspectors from the financial arm of the Paris police, were interested in the accounts of the Bastia club and particularly the transfer of Ghanaian midfielder Mickael Essien from Bastia to Lyon, a legal source said.

The police were assisting a judge, Philippe Courroye. He is investigating Charles Pieri, a fervent Bastia supporter who is widely reported to have links to the Ligue 1 Corsican club.

Four members of the Paris financial arm also visited the Lyon club and the home of Jean-Pierre Bernes, the agent involved in Essien's transfer this year.

Pieri was sentenced to three years in prison in June 2000 for possessing arms.