Moscow and Washington exchanged pin-prick sanctions over Russia's ever-closer annexation of Crimea.

US President Barack Obama opened the bidding by announcing the targeting of 20 Russian individuals, including Sergei Ivanov, a close associate of Vladimir Putin, and a private bank owned by Yuri Kovalchuk, another ally of the Russian president.

Moscow responded by imposing entry bans on nine US politicians.

The European Union joined in the huffing and puffing, with German Chancellor Angela Merkel warning that the EU was preparing further sanctions and would not take part in any meetings of the G8, which Russia currently chairs.

"So long as there aren't the political circumstances, like now, for an important format like the G8, then there is no G8. Neither the summit, nor the format," she told the Bundestag.

Mr Putin called a meeting of some of Russia's richest oligarchs in Moscow, proposing that businesses "ought to register on Russian territory and pay taxes in our motherland" rather than risk overseas sanctions.

None of this fazed theDuma, which voted 445-1 to approve acceptance of Crimea's return to Russia.

United Russia parliamentary leader Vladimir Vasilyev raised the question of protecting Russian speakers elsewhere in Ukraine from ultra-nationalists.

"They don't understand in Washington that entire territories will flee as Crimea did if such outrage continues," he suggested.

In Crimea, pro-Russian forces took control of two Ukrainian warships in Sevastopol.

However the Russian military and local Crimean militia released Ukrainian naval commander Rear Admiral Sergei Haiduk who had been held for several hours after the surrender of Ukraine's naval HQ in Sevastopol.

The coup leaders have said that they want Ukrainian armed forces to relocate from Crimea, but many have already switched sides, joining the Russians.

Kiev announced that it will leave the Commonwealth of Independent States, a loose alliance of 11 former Soviet republics.