A Russian ship carrying vital fuel to a remote Alaskan port could finally deliver its load Saturday after battling through some 300 miles (480 km) of Arctic ice, the US Coast Guard said.

Helped by a US Coast Guard ice-breaker, the Russian tanker Renda was within seven miles of the port of Nome by late Friday, but was proceeding very cautiously for its final approach.

"They're trying to identify the best course and the best place to navigate into so that the Renda can get as close as possible but that she'll also be able to leave at the end of this," said spokeswoman Veronica Colbath.

"We're almost there but we're not completely there yet, and there's still a lot of moving parts to this operation," she told AFP, adding that the Russian tanker has about a mile of hose on board for the delicate operation.

The Russian ship is carrying 1.3 million gallons of fuel for Nome, a city of some 3,500 people which did not get its usual pre-winter oil delivery due to a storm in the fall.

It is the first time such a fuel delivery has been attempted through some 300 miles of ice in the depths of winter, and wind and currents have made progress through the ice difficult.

The Renda, traveling in the wake of the US cutter Healy, has had to be repeatedly helped by the ice-breaker after ice built up around it, said the Coast Guard spokeswoman.

The bone-chilling weather is harsh even by Alaska's standards: the Coast Guard spokeswoman said temperatures had been down to minus 50 degrees on the two vessels.

A special waiver had to be granted to allow the Renda to head to the rescue, as normally only US-owned and operated vessels would be allowed to make such deliveries, under a 1920 US law.

By Friday everything was set for the Russian ship to deliver its load, but the Coast Guard would not speculate on whether the operation would in fact happen Saturday.

"They still have to get the Renda close enough that the hose can reach, and they still have to make sure that wherever the Renda is moored up that she'll be able to get out as well," said Colbath.

Once hoses are connected, the fuel transfer operation is expected to take some 45 hours, pumping continuously day and night until the fuel is all delivered, officials say.

A path has been cleared through the snow on a beach with a good view of the harbor for townspeople to watch the action, but red-tipped stakes have been placed in the ice to mark off an out-of-bounds area where the hoses will run.

All that can be spotted from shore are two white pea-sized lumps in the distance that are the ships.

"We cannot say at this time when the transfer will start because after the Renda is in place they will have to wait until the water refreezes around it to help keep it stable," said another Coast Guard spokeswoman, Sara Francis.

Even once it has started transfering it is difficult to predict exactly how long the operation will take, since the extreme temperatures could interfere with how fast the fuel can be pumped.