The Faina, carrying tanks and other heavy weaponry, was seized by Somali pirates on September 25. The email stated there are 18 Ukrainians and three Russians on board.
"We have been here for 47 days already. Provisions, fresh water, fuel have finished," the editor of the Sovfracht Maritime Bulletin, Mikhail Voitenko, quoted the crew as saying in the letter.
The Russian captain of the Faina, Vladimir Kolobkov, died of a heart attack after the vessel was seized, and his body is still on board. The pirates holding the ship have reportedly demanded a $5 million ransom, and threatened to kill the hostages if a military operation is launched against them.
The crew said they had attempted to contact the owner of the vessel and director of the Tomex crewing company on Tuesday, but Viktor Murenko refused to talk to them and forwarded their request to a London-based lawyer.
Ukraine's Foreign Ministry reported on Tuesday the health of the crew aboard the Faina was satisfactory and also said that supplies of food and drinking water had been recently delivered to the ship.
Pirates are increasingly active in the waters off Somalia, where more than 60 ships have been attacked so far this year resulting in the seizure of around 30 vessels. The East African nation has no effective government and no navy to police its coastline.