* Nine people still missing
* Two of those killed were rescuers
* Bosphorus Strait remains open (Updates death toll, adds minister)
By Ece Toksabay
ISTANBUL, Dec 4 (Reuters) - At least three people were killed and nine others were missing after a cargo ship with a Ukrainian and Russian crew sank in a storm off Istanbul's Black Sea coast on Tuesday.
Two of those who died were rescuers killed when their boat hit rocks in swollen seas as they set off to search for survivors, shipping agency GAC Turkey said. Two other members of that rescue team were missing.
The Volgo Balt 199, which was carrying coal and had 11 Ukrainian and one Russian crew on board, sent an SOS signal at 0730 GMT off the town of Sile on Istanbul's provincial coast but contact with the vessel was lost shortly afterwards.
"Four people were rescued from the ship and one person was found dead. Rescue work continues to find others," Transport Minister Binali Yildirim told reporters.
"Conditions are getting worse because of bad weather. Rescue work is under way with the help of helicopters and boats from the coastguard," he said.
Oleksiy Agafontsev, director of Valship, the operator of the cargo ship, confirmed that four crew members had been rescued and one killed.
A second cargo ship with 14 crew members on board had experienced mechanical failure and was also at risk of sinking, GAC said. Television images showed the second vessel listing heavily in high seas.
Sile lies about 40 km (25 miles) east of the northern end of the Bosphorus Strait, the only maritime outlet for cargo from Black Sea countries, including Russian oil and grain.
Bad weather frequently forces the strait's closure in winter, but GAC said the Bosphorus remained open on Tuesday. About 10,000 vessels carrying 150 million tonnes of oil and petroleum products use the strait every year.
(Additional reporting by Olzhas Auyezov in Kiev; Writing by Nick Tattersall; Editing by Michael Roddy)