Salvage experts warn of a pollution risk

The strength of the MV Willy's cargo tanks has been tested in advance of the rescue operation, which was beginning just before low tide at 1000 GMT.

The tanks are being filled with compressed air to force water out of the bottom of the vessel.

High tide is at 1600 GMT and it is hoped that the ship will be afloat by 1300 GMT.

If that happens she will be accompanied on a journey to Falmouth by four other vessels and a plane.

Mr Clark added: "We are cautiously optimistic, there is only a minimal risk of an oil spill, and we have booms to contain it, and pads to soak it up.

Tanker timeline

Tuesday 1 January, 2245 GMT: MV Willy drags anchors and hits rocks. Crew wade ashore. Police set up no-go zone. Wednesday 0515 GMT: Kingsand homes are evacuated amid fears of explosion. Wednesday lunchtime: a safety crew opens holds to clear petrol vapour. Wednesday evening: many villagers go home, despite warnings. Thursday evening: Kingsand 're-opens' as danger fades. Weekend: a floating crane loads salvage gear. Friday: first attempt to refloat ship

"We also have permission from the Department for the Environment, Food and Rural Affairs for aerial spraying of a chemical dispersant."

One of two salvage tugs, the Grey Mammoth and the Grey Test, will accompany the tanker while two emergency towing vessels will steer her course.

It is hoped she might reach Falmouth by Saturday morning.

Once there, the ship will be looked at by insurance assessors to see if a repair is possible.

A spokesman for United Salvage Limited, the company which hopes to see the tanker safely into dry dock, told BBC News Online: "Weather providing, they might just do it... but everything has to go very carefully and slowly."

The grounding of the MV Willy on New Year's Day led to 150 local people being moved out of their homes after fears that vapour-filled tanks could explode.

The 1981-built vessel, whose 12 crew escaped unhurt, was carrying 93 tonnes of intermediate fuel oil, 41 tonnes of gas oil and fives tonnes of lubricating oil.

An operation to remove the oil has been going on for a week.