A REPORT from the California-based International Council on Clean Transportation has called on regulators to curb emissions from "bunker fuel", which it says contains 27,000 parts per million of sulfur dioxide.

The study, reported The Los Angeles Times and The Sydney Morning Herald, called on the UN's International Maritime Organisation to cut allowable sulfur dioxide levels by 90 per cent and allowable nitrogen oxide levels by 95 per cent.

In addition, they said international limits should be developed for fine particles of soot and for carbon dioxide, the leading greenhouse gas widely believed to be contributing to alleged climate change.

The report indicated that it could take a decade or more to implement changes in oil refineries to produce cleaner fuel and to install more effective pollution-control equipment on ships that the environmental lobby might approve.

Oceangoing vessels produce greater quantities of a lethal air pollutant, sulfur dioxide, than all the world's cars, trucks and buses combined, the group said.

Current US standards for diesel trucks and other vehicles limit sulfur dioxide in fuel to 15 parts per million to protect public health. Sulfur dioxide can quickly kill if too much is inhaled rapidly, the group emphasised.

"Ships are one of the world's largest, virtually uncontrolled sources of air pollution," said Alan Lloyd, president of the group sponsoring the report and former secretary of the California Environmental Protection Agency.

"Air pollution from diesel trucks and buses in Europe, Japan, and the US has declined steadily for over a decade. At the same time, air pollution from international ships is rising virtually unchecked."