A Grimaldi Group ro-ro has reported a suspicious approach by what could be a pirate mothership off Benin in West Africa.

Security consultancy Dryad Global said the 2,500-lane-metre Grande Nigeria (built 2003), operated by Grimaldi Group, reported a suspicious approach 106 nautical miles (196 km) south of Cotonou on Thursday.

Local reporting indicates the vessel spotted a small cargo vessel with two skiffs in tow.