The Ukrainian military is "on full combat alert" over a possible invasion by Russian troops massed on the border, Kiev's acting leader has said.
Interim president Oleksandr Turchynov told a ministerial meeting "Our armed forces are on full combat alert. The threat of Russia starting a war against mainland Ukraine is real".
Russia has denied it has any plans to invade eastern Ukraine after its annexation of the Crimean peninsula in March.
Kiev, however, has accused Moscow of orchestrating an armed uprising in the industrial east by Russian-speaking separatists, who have seized government buildings in a number of towns and cities.
Ukraine's army and police appear to be making little progress in a high-profile operation to prevent the rebels expanding their grip over towns in the east.
It came as the International Monetary Fund (IMF) said Russia was already in recession while citing the effect of the Ukraine crisis on investment in the country.
IMF economist Antonio Spilimbergo was quoted by the Interfax news agency as saying "If we define recession as negative growth in two quarters in a row, then Russia from that point of view is experiencing recession"
The IMF has lowered its 2014 growth forecast for Russia to 0.2% from the 1.3% figure it issued on April 8th, Mr. Spilimbergo added.
