SIMFEROPO: The local parliament in Crimea took another step towards seceding from Ukraine on Thursday, asking to become part of Russia as EU leaders held an emergency summit to deal with the worst East-West crisis since the Cold War.

Pro-Moscow lawmakers made the request to Russian President Vladimir Putin and said they would put the question to a referendum on March 16 as Russian forces maintained their grip on the strategic Black Sea peninsula.

The referendum, which was brought forward from a planned March 30 date, will also ask if residents want to a return to a previous 1992 constitution that gave the region sweeping autonomy.

Tensions ran high on the rugged peninsula, where military observers from the Organization for Security and Co-operation in Europe were set to begin a monitoring mission later on Thursday.

The 40 monitors from 21 OSCE countries were invited by Ukraine, which is in a standoff with local authorities after a Kiev court ordered the arrest of Crimean leader Sergiy Aksyonov for separatism.

'Miracle that bloodshed has been avoided'

“It's extremely tense and I consider it a miracle that bloodshed has been avoided so far,” Tim Guldimann, personal envoy of the Swiss chair of the OSCE, said in Kiev after returning from Crimea.

“Apart from the presence of these military personnel, a very dangerous aspect is the build-up of self defence militias who are armed,” he said.

Guldimann said he cut short his visit after UN special envoy to Crimea Robert Serry was forced to leave on Wednesday after being confronted by gunmen who said they had orders to take him to the airport.

The majority Russian-speaking Crimea has been embroiled in crisis for over a week, following the ouster of Ukraine's pro-Moscow president Viktor Yanukovych.

Russian forces on the territory, home to Kremlin's Black Sea Fleet, have surrounded Ukrainian military bases for days and on Thursday also scuttled an old warship at the entrance of a lake, trapping Ukrainian vessels.

Inside the Ukrainian bases, nervous soldiers were standing their ground, refusing to surrender or hand over their weapons, but in most cases clearly not ready to hold off a full-out Russian assault.

“Of course we are worried, anything can happen. It's a very dangerous situation,” said Lydia Kuzminichna, a 72-year-old doing errands in the regional capital Simferopol.

Crimea had been part of Russia since the late 18th century and was transferred to Ukraine as a “gift” by a Soviet leader in 1954.

Ukraine's prime minister Arseniy Yatsenyuk, who took over after Yanukovych fled to Russia following three months of deadly protests, accused Moscow of stoking tensions.

“It depends on Russia (if) it is ready to fix this conflict ... or is Russia reluctant and (wants) to increase tension,” said Yatsenyuk, who met with European leaders ahead of the summit in Brussels.

Russia 'rewriting borders'

Lithuanian President Dalia Grybauskaite said a “dangerous” Russia was trying to redraw Europe's borders with its actions in Ukraine with “internationally unpredictable behaviour”.

“Today it is an open and brutal aggression, that is exactly what is happening,” she told reporters, adding: “This is about rewriting of the borders”.

In the worst East-West crisis since the Cold War, French President Francois Hollande has asked the EU to “put as much pressure as possible on Russia... to lower tensions and open the way to dialogue”.

Ahead of the summit the EU froze assets held by 18 Ukrainians accused of embezzlement, including the ousted Yanukovych and his son Oleksandr, and some member states were talking about further political and economic sanctions against Russia.

The US and the EU have promised billions in aid for the fledgling government in Kiev after Russia froze the bailout it had agreed with Yanukovych, pushing the former Soviet republic to near-bankruptcy.

US Secretary of State John Kerry will hold a second round of talks with his Russian counterpart Sergei Lavrov, as well as EU foreign ministers later Thursday in Rome and the UN Security Council will hold talks in New York, the body's fourth consultations on the subject since Friday.

Kerry said he was hopeful of a “de-escalation” in the stand-off after meeting Lavrov on Wednesday, although there were no diplomatic breakthroughs.

Violent protests have also broken out in cities in mainly Russian-speaking eastern Ukraine, where several local government offices have been taken over by crowds of angry pro-Russian militants.

Ukrainian police on Thursday seized back control of the regional government headquarters in Donetsk, a day after the building was taken over by activists who had planted a Russian flag on the roof.