Volunteers of the Ukrainian battalion 'Donbass' stand guard at their camp US President Barack Obama warned Sunday that the West would take further measures against Moscow's "provocation" in Ukraine, where tensions are running high over the kidnapping of an international team of observers. Obama called for global unity over the crisis as Europe and the US prepare fresh sanctions against Moscow that are expected to come into force as early as Monday.
AFP reporters in the flashpoint city of Slavyansk in eastern Ukraine said rebels had reinforced the SBU security service building where OSCE monitors are being held and that tensions were growing at checkpoints.
Militants outside the SBU building ordered reporters to leave the vicinity.
Pro-Russia militias have occupied a string of towns and cities in eastern Ukraine, sparking a military response from the Ukrainian army, which is laying siege to Slavyansk, the epicentre of the unrest.
As nerves around the world jangled over the standoff, a Western diplomat has said a Russian invasion of Ukraine in coming days could not be ruled out, with some 40,000 troops poised on the border.
Ukrainian Prime Minister Arseniy Yatsenyuk cut short a trip to the Vatican on Saturday to rush home to deal with the crisis, with has plunged East-West relations to their lowest point since the Cold War.
He has accused Russian warplanes of multiple incursions into Ukrainian airspace and warned that Moscow is trying to provoke Kiev into starting "a third world war".
- 'Not lifted a finger' -
Speaking in Kuala Lumpur during his Asia tour, Obama said Russia had "not lifted a finger" to implement a deal struck in Geneva on April 17 aimed at easing the crisis.
"So long as Russia continues down a path of provocation rather than trying to resolve this issue peacefully and de-escalate it, there are going to be consequences and those consequences will continue to grow," he said.
He spelled out clearly what he expected Russia to do to defuse the crisis and avoid further sanctions on its recession-hit economy.
Moscow should call on the militants in eastern Ukraine to leave occupied buildings and "participate with international observers and monitors rather than stand by while they are being bullied and in some cases detained by these thugs," Obama demanded.
Russia's envoy to the Organisation of Security and Cooperation in Europe has said that Moscow will take "all possible steps" to secure the release of the OSCE team.
The Vienna-based OSCE told AFP that eight of its observers had been detained in Slavyansk since Friday -- four Germans, a Pole, a Dane, a Swede and a Czech.
Ukrainian authorities confirmed that five of its military personnel were travelling with the observers, whose mission is to assess the implementation of the Geneva accord.
The chief of the insurgents' self-styled "Republic of Donetsk", Denis Pushilin, has accused them of being "NATO spies" and offered to release them only as a prisoner swap.
Self-declared mayor of Slavyansk, Vyacheslav Ponomaryov, said those detained had "nothing to do with the OSCE" and were "military personnel".
Ukraine's own security services said they being were held as "human shields" in "inhuman conditions" and that one of the group required urgent medical attention that was being denied.
- 'Move swiftly' on sanctions -
The Group of Seven leading economies and the European Union are readying sanctions that could be announced as soon as Monday in a bid to raise the pressure on Russian President Vladimir Putin.
In a statement on Saturday, the G7 -- comprising the United States, Britain, Canada, France, Germany Italy and Japan -- said they would "move swiftly to impose additional sanctions on Russia" over Ukraine.
The EU said top officials would meet on Monday to weigh further sanctions on Moscow. A diplomat in Brussels said a list adding 15 people to the 55 Russians and Ukrainians already blacklisted by the EU had been approved in principle.
The US and EU have already targeted Putin's inner circle with visa and asset freezes and imposed sanctions on a key Russian bank.
US officials said the next round would target "individuals with influence on the Russian economy, such as energy and banking" and could be bolstered if the situation escalated.
Obama stressed the need for a unified response.
"It's important that we are part of an international coalition sending that message and that Russia is isolated in its actions," he told reporters in Kuala Lumpur.
It was vital to avoid "falling into the trap of interpreting this as the US is trying to pull Ukraine out of Russia's orbit, circa 1950. Because that's not what this is about," he stressed.
"We're going to be in a stronger position to deter Mr Putin when he sees that the world is unified and the United States and Europe are unified rather than this is just a US-Russian conflict," Obama said.
He stressed the need for a "diplomatic path" to resolve the crisis and his Secretary of State John Kerry late Saturday called his Russian counterpart Sergei Lavrov to express concern over "provocative" Russian troop movements.
Lavrov called for "urgent measures" to defuse the crisis, above all urging the end of Ukraine's military operations in the east.
The confrontation escalated after Russia refused to accept the legitimacy of Kiev's new pro-EU government, which came to power in February after four months of street protests forced the ouster of the Kremlin-backed president, Viktor Yanukovych.
Last month, Moscow annexed Ukraine's Crimean peninsula after deploying troops, sparking international outrage.
While Obama has ruled out sending US or NATO forces into Ukraine, Washington has begun deploying 600 US troops to bolster NATO's defences in nearby eastern European states.
Source: AFP