Ukrainian opposition leader Arseniy Yatsenuyk has been sprayed with paint by an unknown attacker.
The incident happened as he was leaving hospital after visiting former Ukrainian Prime Minister Yulia Tymoshenko .
Tymoshenko who has been jailed for abuse is considering an appeal on her request to ease the conditions of her custody.
President Yanukovych has been urged to free her by the EU which claims her detention is political, but the president has refused.
In November he pulled back from a landmark pact with the EU in favour of closer ties with Russia, triggering massive protests that have gone into a third month.