The upper chamber of the Russian parliament...

The deal, signed by the presidents of Russia and Ukraine last week, will come into force as soon as the signatories formally notify each other that they have completed all ratification procedures.

On Tuesday, the lower chamber of the Russian parliament, the State Duma, and the Ukrainian parliament simultaneously ratified the deal extending the lease on the Russian naval base in the Ukrainian port of Sevastopol for 25 years after the current lease expires in 2017. In return, Ukraine will receive a 30% discount on Russian natural gas.

The debate in the Ukrainian parliament saw chaotic scenes, with brawls and eggs thrown at the speaker by opposition lawmakers.

MOSCOW, April 28 (RIA Novosti)