The threat of piracy in West Africa is rising to "critical" levels after the end of the monsoon season, with two more tankers involved in incidents.

Piracy reporting body MDAT-GoG and security consultancies Ambrey and Dryad Global reported that Torm's 50,000-dwt Torm Alexandra (built 2010) was boarded 300km south of Cotonou while en route from Lome in Togo.

The Danish shipowner was "relieved" to be able to say its valued seafarers were safe and accounted for.