+++Live updates of Crimea crisis+++

21:35 - The UN Security Council is meeting for the fourth time in less than a week to discuss the crisis in Ukraine. The meeting was convened at Britain's request. Talks are set to look at Thursday's decision by the Crimean parliament to call a referendum on joining the Russian Federation.

21:00 - Former Ukrainian Prime Minister Yulia Tymoshenko calls for Europe to take strong action over the Crimean parliament's attempt to join Russia. Speaking at a meeting of the center-right European People's Party grouping in Dublin, she warns of a destabilization of the continent otherwise.

18:25 - US Secretary of State John Kerry elaborates on US sanctions imposed in response to Russia's intervention in Crimea. The State Department has imposed visa bans against those responsible for violating Ukraine's sovereignty, including people who have claimed authority in Crimea without Ukraine's authorization. President Obama has provided the US Treasury Department with the legal authority to freeze the financial assets of those who allegedly caused the crisis. The White House provided a legal framework for economic sanctions, instead of immediately imposing them, in order to retain flexibility in negotiations with Moscow.

18:10 - In a televised statement, US President Barack Obama says that the proposed referendum in Crimea violates the Ukrainian constitution and international law. The president went on to say that international observers should be deployed in all of Ukraine, as well as Crimea, to ensure the rights of ethnic Russians. The US and the EU are united in their response and Congress should make American resources available to the government in Kyiv, according to the US president.

17:45 - The international policing network Interpol says it has received a request from Ukrainian authorities for the arrest of ousted President Viktor Yanukovych, on charges of abuse of power and murder. The request is currently being assessed by Intterpol’s Office of Legal Affairs. Yanukovych is believed to have fled to Russia, which is a member of Interpol.

17:24 - The US ambassador to Poland says Washington will boost joint military exercises with Warsaw to reassure allies in light of the crisis in Crimea, according to the Reuters news agency. The Polish defense minister confirms that 12 US F-16 fighter jets and 300 US troops will arrive in the country next week for a training drill.

17:23 - Ukraine's national parliament begins legislative procedures to dissolve the regional assembly in Crimea, according to interim President Oleksander Turchynov.

17:19 - German Chancellor Angela Merkel calls on Russia to hold direct talks with Ukrainian government and says pro-Russian forces in Crimea must be disarmed. Merkel went on to say that if Russia doesn't take steps to de-escalate the situation, economic sanctions will be imposed.

16:58 - The EU decides to suspend bilateral talks with Russia on visa liberalization in response to its intervention in Crimea. EU Council President Herman van Rompuy says that the 28-member bloc will impose travel bans, asset freezes and cancel the EU-Russia summit if Moscow does not take steps to de-escalate the situation in Ukraine. The EU will also sign the political chapters of an association agreement with Kyiv before Ukrainian elections scheduled for May 25th, according to van Rompuy.

16:35 - International observers with the Organization for Security and Cooperation in Europe (OSCE) are denied access to Crimea. The 43 observers from 23 OSCE nations were unable to get past roadblocks. They are supposed to monitor troop movements in Crimea.

16:18 - Russian Foreign Minister Sergei Lavrov says that so far no agreement has been reached on Ukraine in talks with US Secretary of State John Kerry in Rome. Lavrov says he will "study" Kerry's suggestions on defusing the crisis in Crimea, according to Russian news agencies.

15:47 - A US destroyer, equipped with guided missiles, is on its way to the Black Sea for a "routine" deployment, according to navy officials. The USS Truxtun shipped off from the Greek port of Souda Bay on Thursday to carry out joint exercises with Romanian and Bulgarian forces.

15:44 - NATO has beefed up its air patrols over the Baltic states. According to Lithuania's defense minister, six US fighter jets will join four other warplanes patrolling the air space of Lithuania, Latvia and Estonia.

15:19 - In a joint press conference with NATO chief Anders Fogh Rasmussen, Prime Minister Yatsenyuk says that Ukraine is not planning on joining NATO.

15:04 - Consultations between the leaders of the EU's 28 member states on whether or not to impose sanctions against Russia are extended.

14:15 - In a press conference in Brussels, Ukrainian Prime Minister Arseniy Yatsenyuk urges Russia to withdraw its troops in Crimea to their barracks. The premier calls Crimea's move to hold a referendum on joining the Russian Federation "illegitimate." He went on to say that Kyiv wants to sign an EU association agreement as soon as possible.

13:22 - The decision by Crimea's parliament to secede from Ukraine is effective immediately, according to statements from the regional government. Russian troops are the only legitimate forces on the peninsula, Crimea's vice premier said. Ukrainian troops will subsequently be viewed as occupiers, he added.

13:05 - US President Barack Obama signs an executive order imposing targeted sanctions against unidentified people and organizations allegedly responsible for the pro-Russian military intervention in Crimea. The president's order bans travel to the US and paves the way for freezing the financial assets of those involved in the military intervention.

slk/rc (AP, AFP, dpa, Reuters)

All updates in Coordinated Universal Time (UTC)