Ice over the Kerch Strait which links the Sea of Azov to the Black Sea has trapped 126 boats as southern Ukraine remained in the grip of an abnormally cold snap, the emergencies ministry said on Thursday.
"One hundred and twenty six boats, including 120 foreign ones, are anchored in the Kerch Strait," the ministry said in a statement.
It did not specify the nationality of the vessels, nor the number of their crew.
The Kerch Strait is a narrow but busy artery that connects the Sea of Azov to the Black Sea, and separates Russia from Ukraine.
"The ice has totally covered the Kerch Strait," the ministry said, adding that icebreakers can only provide assistance to boats in good weather conditions.
Ukraine has been hit by a spell of extremely cold weather, with temperatures fluctuating Thursday between minus 11 and minus 17 degrees Celsius (12 and 1 degrees Farenheit).
They may drop as low as minus 30 degrees Celsius (-22 degrees Farenheit) in some regions over the weekend, weather forecasters said.