Women and a boy with a toy Kalashnikov rifle walk past an unfinished wall painting depicting a map of Crimean peninsula and a slogan reading "Together Forever" in Moscow, on Monday. Photo: AFP

US President Barack Obama on Monday vowed Western unity in punishing Moscow for annexing Crimea, ahead of crisis talks that could see Russia excluded from the G8 club of rich nations.

In Ukraine itself, the country's acting president announced that its troops had been given orders to withdraw from Crimea after the fall of another military base to Kremlin troops.

Meanwhile, Russian Defense Minister Sergei Shoigu on Monday inspected troops and military facilities in Crimea and also met Crimea's pro-Moscow Prime Minister Sergei Aksyonov, the first senior Russian official to travel to the Black Sea peninsula since Moscow absorbed the region, state television said.

"Europe and America are united in our support of the Ukrainian government and the Ukrainian people," Obama said after a meeting with Dutch Prime Minister Mark Rutte. "We're united in imposing a cost on Russia for its actions so far. Prime Minister Rutte rightly pointed out yesterday the growing sanctions would bring significant consequences to the Russian economy."

Obama then headed to The Hague where he has called an emergency G7 summit to discuss what steps to take in the worst East-West standoff since the Cold War.

Obama, who has imposed tougher sanctions on Moscow than European leaders, will seek support for his firm line at the G7 meeting that excludes Russia.

The G8 group will not meet in Russia this year, British Prime Minister David Cameron said on Monday.

Russia said Monday it had banned entry to the country for 13 Canadian lawmakers and public figures, after Canada imposed sanctions against seven Russian and three Crimean senior officials over the crisis in Ukraine.

Russian troops have rapidly overrun the Black Sea peninsula since the fall of a pro-Moscow government in Kiev a month ago.

"The national security and defense council has reached a decision, under instructions from the defense ministry, to conduct a redeployment of military units stationed in the Autonomous Republic of Crimea," acting Ukraine President Oleksandr Turchynov told lawmakers.

Crimea's pro-Kremlin Deputy Premier Rustam Temirgaliyev told Russia's RIA Novosti state news agency that "all Ukrainian soldiers have either switched to the Russian side or are leaving the territory of the Crimea."

In the meantime, Russian Prime Minister Dmitry Medvedev said on Monday that Moscow plans to end Crimea's reliance on Ukraine for electricity by helping to build gas-fired power stations and possibly linking the region to Russia's grid.

AFP - Reuters