Rival protests take place in Ukraine amid military tensions

(Vatican Radio) Germany's Angela Merkel delivered a rebuke to President Vladimir Putin on Sunday, telling him that a planned Moscow-backed referendum on whether Crimea should join Russia was illegal and violated Ukraine's constitution.

Putin defended breakaway moves by pro-Russian leaders in Crimea, where Russian forces tightened their grip on the Ukrainian Black Sea peninsula by seizing another border post and a military airfield.

Also on Sunday, Pro-Russian activists attacked a pro-Kyiv rally on Ukraine's Crimea's peninsula with clubs and whips on Sunday as thousands took to the streets across Ukraine in rival demonstrations, escalating separatist tensions in the troubled ex-Soviet state. The protests came while Interim Prime Minister Arseniy Yatsenyuk vowed Ukraine would not cede “an inch” of its territory to Moscow.

Yatsenyuk was reportedly to visit Washington for consultation, after pro-Russian forces prevented more than 40 international observers from entering Crimea, after taking control over military bases across the area.

The observers from the Organisation for Security and Cooperation in Europe (OSCE) even faced warning shots, explained Hungarian Gábor Ács, who heads the mission.

“We tried for the fourth time to enter the Crimean Peninsula. Unfortunately it was again unsuccessful. At this moment they were much more angry than the previous time especially towards the Ukrainian escort," he said.

The incident underscored international concerns over what Ukraine's interim government has called a Russian armed invasion with as many as 30,000 Russian forces effectively controlling the region.

OBAMA APPEAL

U.S. President Barack Obama, who discussed the situation with leaders from Britain, France, Italy and the Baltic states said in a statement he agrees with European leaders that Russia must pull back its forces from Crimea.

He also urged Russia to allow international monitors as well as human rights observers to work there and to support fair presidential elections in May.

At Washington Brookings Institution, non-proliferation scholar Steven Pifer warned the crisis urgently needs to be de-escalated

“Russia and Ukraine right now are one nervous 20-year-old soldier's mistake away from something very, very bad happening that could spin out of control,” he explained.

There seems little time left as already troops, believed to be Russian, drove a truck into a missile defence post in Sevastopol the home of both their Black Sea Fleet and the Ukrainian navy.

SURROUNDING BASES

And Ukraine’s border service has said that Russian troops also seized a border guard outpost in the east of the peninsula, after surrounding several bases across Crimea.

The military movements come ahead of a March 16 referendum in Crimea on whether to join Russia. The proposed referendum has been condemned by Ukraine's government and by western leaders as unconstitutional and illegal.

Central and Eastern European countries near Ukraine have expressed concern that the crisis could impact them after Russia warned the interim Ukrainian government of another possible shutdown over unpaid gas bills.

The same pipelines that bring Russian gas to Ukraine also supplies eastern Europe, creating shortages there.

The Czech Republic, Hungary, Poland, and Slovakia have urged the U.S. to make it easier for them to import American natural gas, to reduce their reliance on Russia, their former Soviet master.

Listen to Stefan Bos' report: