LE HAVRE?Three Russian sailors found dead aboard their oil tanker passing through the Channel were poisoned by adulterated alcohol, a French prosecutor said Friday.

The tanker Arionas, en route from Bahrain to the Netherlands with a cargo of aviation fuel, was diverted to Le Havre on Wednesday after its captain reported the fatalities by radio.

"The deaths resulted from the absorption of adulterated alcohol bought while in port without the captain's knowledge and despite the formal prohibition of consuming alcohol on board," said prosecutor Francis Nachbar.

The adulterated drink could have contained methyl alcohol, he said, which could kill with just half a glass.

While the empty bottle was found by authorities it was not clear in which port the sailors aboard the Marshall Islands-registered ship may have purchased the alcohol.