Citing environmental rules, ExxonMobil says it will phase out the sale of marine bunker C fuel to commercial shippers in the Port of Halifax as part of its decision to close its Imperial Oil refinery in Dartmouth, N.S.

Last week the company announced it will convert the 95-year old refinery to a large import terminal by year end.

"In anticipation of coming changes to environmental regulations for marine fuel, the terminal operation will transition from marine bunker fuel sales, and replace this product offering with cleaner burning marine diesel fuel," ExxonMobil Canada spokesman Merle MacIsaac wrote in an email.

Bunker C fuel oil is the most sticky and thick of the residual fuels, and is typically used by ships, industrial boilers and power generating stations.

Since Imperial officials made the announcement, the Port of Halifax has been acutely interested in the future of marine fuel sales.

"Ideally for us, we'd like to see service maintained," port spokesperson Lane Farguson told CBC News.

"We're watching this very closely because, as you know, we are a full service port. What that means for commercial vessels, cruise lines, they know they can get fuel supplies, water and supplies."

"It’s important to us to find out what’s going on."

It’s not clear what other fuel services will remain.

Exxon said it was too early to comment on whether the terminal in Dartmouth will accept crude or refined product only or whether the site will also blend fuels.

"Where there are any changes to a product offering, Imperial Oil will work closely with its customers to support a smooth transition," said MacIsaac.

Imperial Oil will refine its last barrel later this year.

About 400 people have work ties to the refinery. About 80 employees will either retire or stay on. The company said the rest will be offered work elsewhere in Canada.

The refinery produces most of the gasoline sold in Nova Scotia.