Russian President Vladimir Putin has offered his sincere condolences to the relatives and friends of the Crimean blast victims, Kremlin Spokesman Dmitry Peskov has told the media.

"The president offers deep condolences to those who lost their relatives and dear ones as a result of this explosion," he said.

An explosion at a technical college in Kerch on Wednesday claimed ten lives, according to the latest reports.

Several dozen other people are said to have been injured. The National Antiterrorist Committee has said an unidentified explosive device went off.