Skuld is warning shipowners that ship-to-ship transfers in Malaysia, Africa and the Caribbean could unwittingly expose them to sanctions risk.

The Norwegian protection and indemnity club said in a note on Tuesday that owners should be cognisant of the tactics counterparties might use to move cargoes subject to US sanctions amid growing oil exports from Iran and Venezuela.

"Many [ship-to-ship] transfers are legitimate; however, suspicious circumstances such as operations at night and in high-risk areas, anchoring or drifting near sanctioned countries, and missing AIS data should raise immediate concern," Skuld said.