HAVANA (REUTERS) - Seven Cubans have died and more than 40 have been hospitalised, eight in critical condition, after drinking wood alcohol, or industrial methanol, they thought was rum, the public health ministry said on Wednesday.

The poisoning happened in the La Lisa municipality of Havana, beginning on Monday, and all those killed were in their 40s and 50s, according to a list provided by the ministry.

Such incidents are rare, though not unheard of in Cuba.

"Those affected consumed wood alcohol sold illegally... that was supplied by two individuals who work in the Pharmacy and Food Institute and took it from the local warehouse," the ministry said in a statement.

"Wood alcohol is extremely toxic and causes headaches, nausea, blindness and death," the ministry said, urging residents to seek medical attention if they suffer from any symptoms.

Also known as methanol or methyl alcohol, wood alcohol is commonly used as a solvent in medical laboratories and as a fuel or anti-freeze.