ABIDJAN (Reuters) - Côte d'Ivoire authorities have arrested 15 people in connection with an attack claimed by al Qaeda that killed 19 people at a beach resort this month, a state prosecutor said on Tuesday.

They were still seeking the suspected ring-leader, whom prosecutor Richard Adou named as Kounta Dallah.

Gunmen shot swimmers and sunbathers before storming into several hotels when they burst onto the beach in the town of Grand Bassam, 40 km (25 miles) from the commercial capital Abidjan, on March 13.

"Evidence found at the scene has allowed us to identify and trace certain individuals who participated in these acts," Adou told a news conference.

Adou gave no further information on those arrested, declining to give their nationalities out of concern that their countrymen living in or visiting Côte d'Ivoire could become the target of violent reprisals.

He showed reporters a photo of Dallah that appeared to have been taken during an airport passport inspection. No other details about the suspect were available.

"This person is directly involved in the attack, was recognised by witnesses ... He was present at the scene, but left at a certain moment," Interior Minister Hamed Bakayoko told reporters.

"Concerning him, there is no doubt. The arrests that followed are a community of individuals who were with him, who have links to him," he added.

Weapons, ammunition, balaclavas and vehicles believed to have been used by the attackers were being examined and a judge was preparing both domestic and international arrest warrants for other suspects.

Eleven Ivorians, including three special forces' soldiers, died in the shooting rampage. Four French citizens were killed and other foreign victims included citizens of Germany, Lebanon, Macedonia and Nigeria.

Adou said that Ivorian authorities had received assistance from a team of French investigators, the U.S. Federal Bureau of Investigations as well as law enforcement officials from Germany, Morocco and Mali.

Al Qaeda in the Islamic Maghreb (AQIM), the group's North African affiliate, announced that it was responsible for the Grand Bassam assault and posted the photos of the three suicide attackers it said had carried it out.

Interior Minister Bakayoko said the investigations had not been able to confirm that they were the same three men killed by Ivorian security forces on the beach.

Reuters