Environmental groups want the eight countries that ring the North Pole to take a stand on banning the use of heavy fuel oil, considered one of the greatest threats to the Arctic ecosystem.

"We believe that measures are desperately needed to reduce the environmental impacts from Arctic shipping, and that a logical place to focus attention is vessel fuel quality," said the letter from 15 international environmental groups to the Arctic Council.

"The risks to the marine environment, the climate, and public health are too great to permit the continued use of (heavy fuel oil) in Arctic shipping."

A Canadian-led branch of the council is to consider the issue in three days of meetings starting Monday in Stockholm.

The dangers of heavy fuel oil, which powers almost all the large cargo ships that ply circumpolar waters, have been well-documented in previous studies.

Unlike other fuels, heavy fuel oil doesn't evaporate. Instead, it combines with seawater and actually expands in volume. It also sinks and sticks to anything it contacts, making cleanup impossible -- as suggested by a recent spill in Russian waters that killed hundreds of seabirds.

"There's just no way to respond to it," said Kevin Harun of Pacific Environment, an environmental group that works with aboriginal communities to protect the Pacific Rim.

As well, burning heavy fuel oil creates so-called "black carbon," a fine soot that falls on snow and ice and hastens its melt. Cleaning up black carbon has been identified as one of the easiest and quickest ways to slow the retreat of Arctic sea ice.

Reducing black carbon has been a top priority for the Arctic Council both during Canada's time as head of the group and the current U.S. chairmanship.

However, the group that sets the rules for international shipping recently declined to ban heavy fuel oil in the Arctic. Bowing to pressure from countries -- such as Russia --which have large merchant fleets that use the fuel, the International Marine Organization left the issue out of the Polar Code it adopted last year.

It's time for the Arctic Council to take the lead, Harun said.

"There's enough information on this to act right now. The question is, will the Arctic Council stand up and do something?"

Russia is also a member of the Arctic Council, a group which has always operated by consensus.

"With this unanimity approach, it's really hard to get anything through the Arctic Council," Harun said.

"But somebody's got to stand up to say this needs to be done now. We're hoping at this upcoming meeting, both the Canadian delegation and the U.S. delegation will assert some leadership.

"It would be a very strong message to IMO if the Arctic Council were to recommend a (heavy fuel oil) ban."

A federal official involved with the meeting confirmed several member countries were bringing forward new reports on the issue. Whether or not a recommendation on banning use of the fuel depends on how the talks go, she said.

Although major spills of the fuel are still rare, Harun said the time to bring in a ban is before problems begin.

Ships running on heavy fuel oil can be converted to run on less harmful fuels.

"We're not talking about stopping commerce," said Harun. "We're talking about stopping a fuel that is very dirty."