A stand-off in the streets of Odessa.

Pro-Ukrainian and pro-Russian protesters clash outside the hotel where Ukrainian presidential candidate Oleg Tsarev was staying.

A bus is attacked and a Ukrainian flag is burned.

This, as Russia's chief prosecutor warns that ousted Ukrainian president Viktor Yanukovich will not be extradited:

(SOUNDBITE) (Russian) RUSSIA'S CHIEF PROSECUTOR YURI CHAIKA, SAYING:

"Yanukovich is a fully fledged, legitimate president. The authorities that are there today came to power - in my opinion, and I speak as a lawyer - unlawfully as a result of an armed coup. We have no grounds for extradition of Yanukovich as Yanukovich is a legitimate president and he didn't commit a crime."

As tensions continue to escalate, Russian President Vladimir Putin warned that gas supplies to Europe could be disrupted by Ukraine's failure to pay its gas bills.

A now fearful Ukraine hopes to buy gas from Europe.

The European Commission ha