Senior Labour MP Keith Vaz, a former Europe minister, said the British people should be given a say as "soon as possible" but former prime minister Tony Blair said a referendum was "not necessary" and effectively put the question of EU exit "on the agenda".
The manager of the care home in Strontian had her staff on standby for possible evacuation, but the fire service said it did not expect that would be necessary at this stage.
French President Nicolas Sarkozy has said "giving people a voice is always legitimate but the solidarity of all eurozone countries is notpossible unless each one agrees to measures deemed necessary".
"We're trying to move it forward as quickly as possible, but it's not easy and straightforward to get a mine opened and to raise all the necessary funding, " operations manager Jeff Harrison said.