Inspectors from the United States and Germany are to make observation flights over Russia and Belarus to verify the true position of Russian military assets following reports that Russian forces are mobilising close to the Ukrainian border.

"The flights will be performed on the Swedish observation plane SAAB-340," Sergey Ryzhkov, head of the National Nuclear Threat Reduction Center, confirmed to Russian News Agency Itar-Tass.

Ryzhkov revealed that the flights would only take place on agreed routes and that Russian and Belarussian representatives would be present on board the observation flights.

Ukraine has accused Russia of moving its military forces close to their shared border as fears grow that the Russian army may invade the Crimean peninsula.

The SAAB-340 aircraft is equipped with aerial photographic cameras but does not hold any weaponry.

The flights are to take place within the framework of the international treaty on Open Skies, signed in 1992 by 34 countries.

The treaty was created to ensure transparency in arms control and the de-escalation of crisis situations.

The Crimean parliament has formally voted to declare independence from Ukraine following an overwhelming outcome from the referendum to secede from Kiev rule and join Russia, according to reports.

A formal application to join Russia was sent after 93% of Crimea residents reportedly voted in favour of the split, in a referendum that the US and the EU say violates the Ukrainian constitution and international law.