Ukraine soldiers in Crimea.
The US and Russia stepped up diplomatic efforts to defuse the Ukraine crisis on Wednesday amid heightened tensions on the ground in the flashpoint area of Crimea as gunmen threatened the UN envoy.
US Secretary of State John Kerry held the first direct talks with his Russian counterpart as Washington warned Moscow it risked losing its coveted G8 place over the worst East-West crisis since the end of the Cold War.
The volatile situation in Eastern Ukraine showed little sign of easing as a dozen people were hurt as pro-Russian protesters took back the regional government building in the city of Donetsk.
And in Crimea, gunmen part-seized a Ukrainian missile facility in Cape Fiolent near Sevastopol, Ukrainian officials said.
Earlier on Wednesday, the European Union unveiled an aid package worth at least €11-billion to support Ukraine's new pro-EU leaders the day after the US announced a $1-billion loan guarantee pledge.
The West continued its strategy of combining support for the new government in Kiev with pressure on a defiant Russia to back down.
US treasury secretary Jacob Lew made clear it was also prepared to act ahead of a summit of G8 leaders in June.
"We are on a path where I think it's clear Russia cannot sit in Sochi at G8 meetings while it's pursuing the policies that it's now pursuing," Lew said.
Lavrov and Kerry were meeting for the first time since Moscow-backed president Viktor Yanukovych was ousted late last month after three months of protests which left nearly 100 dead.
In a bid to end the crisis, US President Barack Obama has outlined proposals including Russian forces returning to their bases in strategically crucial Crimea, home to Russia's Black Sea naval fleet.
Obama also wants the deployment of international observers and the start of talks between Moscow and Kiev, a US official said.
But Russia insists there are no troops from its military operating in Crimea. "If they are the self-defence forces created by the inhabitants of Crimea, we have no authority over them. They do not receive our orders," Lavrov told reporters.
Lavrov is likely to argue that Ukraine's interim government is illegitimate and anti-constitutional, echoing Putin's comments at a press conference on Tuesday.
Western support for Ukraine
As well as Obama's proposals, governments including Britain are urging Lavrov to meet acting Ukrainian Foreign Minister Andriy Deshchytsya to kickstart negotiations.
The EU's biggest powers, France and Germany, want an "exit plan" from the crisis which could be discussed from Wednesday in Paris, French Foreign Minister Laurent Fabius said.
This would include plans for a unity government, the return of Russian forces to barracks, the dissolution of extremist elements, the validity of the 2004 Constitution and the importance of presidential elections.
And a mission of 35 military observers will be sent to Ukraine by the Organisation for Security and Co-operation in Europe (OSCE) in a bid to "help de-escalate tensions", its secretary general Lamberto Zannier said.
A US official said on Tuesday an announcement on Russian sanctions is likely this week.
The EU is set to hold an emergency summit on Ukraine Thursday.
The flurry of diplomacy comes the day after angry public exchanges between the US and Russia which underlined the sense of frustration on both sides.
Obama said on Tuesday Russia was "not fooling anyone" after it claimed it had no troops operating in Crimea and Kerry accused it of an "act of aggression" after visiting the new interim government in Kiev.
Putin had earlier insisted on his right to use "all available means" as a "last resort" in Ukraine during his first press conference since Yanukovych's ouster.
Crimea, east on edge
The potential for a dangerous flare-up in Crimea and eastern Ukraine was underlined Wednesday.
In Donetsk, a stronghold of ex-president Yanukovych, pro-Russian protesters with bloody faces forced their way past police lines to snatch back the regional government building from which they were ousted earlier on Wednesday.
Meanwhile, gunmen part-seized a missile facility in Cape Fiolent near Sevastopol, Ukrainian officials said, apparently without violence.
Russian soldiers were holding some parts of the base although the missile depot itself remains in Ukrainian hands, Volodymyr Bova, a defence ministry spokesperson in the peninsula, told AFP.
At another missile facility in Evpatoria on Crimea's western coast, pro-Russian demonstrators unexpectedly tried to storm a base which pro-Russian soldiers had previously taken over.
Lavrov told a press conference in Madrid that the Russian Black Sea naval fleet were under "special measures of alert and control" but remained in their assigned bases.
Crimea is an autonomous area within Ukraine but is located next to Russia and has a Russian ethnic majority. It is strategically vital, offering access to the Mediterranean within a day's sailing.
Elsewhere on the peninsula, the situation was mostly calm.
In Simferopol, the capital of Crimea, local people were watching the crisis closely. One resident, Sergei, welcomed the presence of thousands of pro-Russian forces. "This is normal because if there were no Russian soldiers, it would be like Kiev here, exactly the same. People calmed down when the soldiers arrived," he said.
Another, Maria, said Ukraine was a united country which must not be divided. "We must live in peace, no matter what language we speak. We need the country to unite so we can live in peace – it doesn't matter if we speak Russian or Ukrainian," she added.
European stock markets fell Wednesday, in part due to uncertainty over the situation in Kiev.
Russia revealed earlier that it sold a record $11.3-billion in foreign currency on Monday to prop up the ruble. That day was dubbed "Black Monday" as concern about the Ukraine conflict sent stock markets falling around the world. – AFP