Countries with poor marine safety tend be involved in the largest oil spills, according to a recent study.

Researchers from the University of British Columbia have determined that more than half of ships involved in the 100 largest oil spills of the past three decades were registered in states that consistently fail to comply with international safety and environmental standards.

The research also found one-third of the current global oil tanker fleet are flying the flags of states with poor marine safety records -- what they term "flags of non-compliance."

"Vessels flying flags of non-compliance create more problems than the rest of the global fleet," Rashid Sumaila, co-author of the study and director of UBC's Fisheries Economics Research Unit (FERU), said in a statement. "We think the best thing to do is to put pressure on flag states to ensure that anyone who uses their flag conforms to the regulations."

Ship owners often register with foreign states for cost-cutting reasons, noted Dana Miller, lead author of the study.

"International law says there should be a genuine link between the nationality of the vessel owner and the flag the vessel is flying, but that is not necessarily always the case," Miller explains. "Just because a vessel owner is using a foreign flag doesn't mean they are irresponsible, but there is recognition by the international community that there are some flag states that are just doing a terrible job. Some would argue that if we don't get rid of the system of flags of convenience, the problem will always persist."

For the study, the researchers consulted data gathered by the International Tanker Owners Pollution Federation; the Information Handling Services Sea-web global database; inspection reports from the United States Coast Guard's annual targeted flag list and seven regional Memoranda of Understanding on Port State Control.

The findings are detailed in the journal Environmental Conservation.