(Clarifies he was given a suspended sentence, corrects fine and damages decision, spelling of adviser's name)
LIBREVILLE, March 29 (Reuters) - A prominent environmental activist was given a six-month suspended sentence for defamation in Gabon, his lawyer said on Friday, after he accused an ally of the president of secretly owning the local unit of commodities giant Olam International.
Marc Ona Essangui said during a television broadcast that Olam Gabon, which is developing timber, palm oil and rubber projects in the tiny Central African nation, belonged to Liban Soleman, a senior advisor to President Ali Bongo.
Soleman denied the allegation and brought a defamation case against him, which he won in a Libreville court.
"I regret this decision against my client, who was only fulfilling his role of a counterweight (to the government). I will consult with my client and possibly appeal this decision," Ona Essangui's lawyer Ruphin Nkoulou said.
The court also ordered Ona Essangui to pay damages of 5 million CFA francs ($9,800) to Soleman as well as a fine of 200,000 CFA francs. The state prosecutor had requested a one-year jail sentence.
During his first appearance in court on March 9, the wheelchair-bound activist said he did not regret making the accusation. "If I had it to do over again, I'd do the same thing," he said at the time.
Olam began operating in Gabon in 1999, establishing a logging operation. It later entered into a joint venture with the Gabonese state to develop plantations and palm oil mills with planned investments of around $236 million.
Gabonese environmental groups have for the past three years requested publication of the joint venture agreement without success.
Ona Essangui was jailed briefly in 2008 after calling for more transparency in the country's public management. ($1 = 510.8300 CFA francs) (Reporting by Jean-Rovys Dabany; Writing by Joe Bavier; Editing by Daniel Flynn and Pravin Char)