OSCE observer mission in Ukraine

outside Simferopol, Ukraine, 04 March 2014. The Russian army reportedly occupied key sites in the autonomous region of Crimea, where a majority of the population is ethnic Russian. Troops surrounded several small military outposts and demanded Ukrainian troops disarm: photo - EPA/MAXIM SHIPENKOV

"2 Polish officers will participate in the OSCE military observers mission from 15 countries, which will start tomorrow [5 March] in the Crimea at the request of Ukraine," Poland's defence minister Tomasz Siemoniak tweeted on Tuesday.

Daniel Baer, the US's chief delegate to the OSCE, said the aim of the mission - which has a week-long mandate, although this could be extended at Ukraine's request - will be to try to prevent a possible “military incursion” in “areas where there has been tension or uncertainty has arisen over lack of clarity over military movements," he told the AP agency.

The delegation is already in Ukraine, said national security chief in Kiev Andriy Paruby

"An OSCE mission has arrived in Kiev, which will go to the Crimean peninsula to monitor the situation," he told a news conference on Tuesday.

The fifteen nations taking part have each sent two observers as tension mounts in south and east Ukraine.

It was not immediately clear whether Russia would allow monitors to enter the Black Sea peninsula, where it controls the airspace and access points. The diplomats said Russia's agreement was not legally necessary, Reuters reports. (pg)