Belarussian President Alexander Lukashenko said Wednesday he would ask Russia to station up to 15 jets in his country in response to NATO's moves over the Ukraine crisis.

"If NATO decided, together with the Americans, to ramp up their air force presence near our borders, what, should we just watch them?" the maverick leader said, speaking at a meeting of his security council.

Hundreds of people have fled Crimea and the situation could deteriorate further as tensions continue to rise on the Russian-controlled peninsula, Ukraine's national security chief warned Wednesday.

"Today there are hundreds of them, but if separatists continue their activities in the Crimea, the number of refugees may increase," National Security and Defense Council Secretary Andriy Parubiy told reporters.

The Group of Seven most developed economies on Wednesday said a Moscow-backed referendum in Crimea on switching over to Kremlin rule would have "no legal effect" and called on Russia to back down.

The G7 -- Britain, Canada, France, Germany, Italy, Japan and the United States -- along with European Union leaders called on Russia "to cease all efforts to change the status of Crimea contrary to Ukrainian law and in violation of international law," according to a statement released by the White House.

Ukraine's acting president told Agence France Presse he would not wage war over Crimea as the ex-Soviet state's premier prepared Wednesday to seek U.S. President Barack Obama's help against Russia's expansionist threat.

The first meeting between Obama and Ukrainian Prime Minister Arseniy Yatsenyuk comes with the nation on the EU's eastern border in danger of breaking apart when the predominantly ethnic Russian region holds a Moscow-backed referendum Sunday on switching over to Kremlin rule.

Russia has signed a preliminary agreement to build at least two more nuclear power plants in the Iranian port city of Bushehr, Iran's official IRNA news agency reported on Wednesday.

The deal was reached during a visit to Tehran on Tuesday by a senior official of Russia's state atomic energy agency Rosatom, IRNA said.

President Vladimir Putin has seen his approval rating climb in Russia due to his strong stance on military intervention in Ukraine, several opinion polls show.

More than two out of three Russians (69 percent of those interviewed), say they back Putin's actions, a poll by the independent Levada agency found in late February after interviewing 1,603 people in 45 regions.

Syrian President Bashar Assad, whose embattled regime relies on key support from Russia, praised Moscow on Tuesday for restoring balance to international relations, state media reported.

"Russia has reestablished balance in international relations, after long years of hegemony" by the United States, SANA quoted Assad as saying as he received a Russian parliamentary delegation.

Pro-Moscow lawmakers in Crimea voted for independence from Ukraine on Tuesday in a precursor to a referendum this weekend for the region to become part of Russia.

The local assembly approved a "declaration on the independence of the autonomous republic of Crimea and the city of Sevastopol" with 78 out of 81 lawmakers present voting in favor.

Ousted Ukrainian leader Viktor Yanukovych on Tuesday said that he was still the country's legitimate president and commander-in-chief, predicting he would be able to return to Kiev soon.

"I remain not just the sole legitimate president of Ukraine but also commander-in-chief," he said in his first public appearance in over a week, in the southern Russian city of Rostov-on-Don.

French Foreign Minister Laurent Fabius warned Tuesday that sanctions against Russia could come as early as this week if Moscow does not respond to Western proposals to solve the crisis in Ukraine.

"If they respond positively (to the proposals), (U.S. Secretary of State) John Kerry will go to Moscow, and then sanctions will not be immediate. If they do not respond or if they respond negatively, there will be a series of sanctions that could be taken as early as this week," he said on France Inter radio.