(Updates death toll, adds transport minister)

KIEV, April 28 (Reuters) - A Ukrainian helicopter crashed onto an offshore drilling platform in the Black Sea on Monday, killing all 20 people on board, an emergencies ministry spokesman said.

Nineteen people were killed on impact and one initially survived, but he later died from his injuries, the ministry said. No one on the platform was injured.

The platform, on the West coast off the Crimea, is operated by state energy firm Naftogaz, which also owned the helicopter.

"An Mi-8 helicopter with 20 people on board clipped the Tavrida platform with its tail rotor," Naftogaz spokesman Ilya Savin said, in explaining how the crash happened.

The transport and communications minister, Yosip Vinsky said the cause of the accident was still being investigated, adding "Judging by the logic of the initial information, most likely there was a human factor".

An Mi-8 belonging to Ukraine's border guards crashed a month ago off an island in the Black Sea, killing 12 people. (Reporting by Pavel Polityuk; Writing by Christian Lowe and Sabina Zawadzki; editing by Ralph Boulton)

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