Ukrainian rebels keep up attacks on government-held airport in Donetsk

KIEV (Reuters) - Ukraine accused Russian forces on Friday of helping separatists step up pressure on government troops holding the main airport in the eastern city of Donetsk, threatening a fragile ceasefire.

Military spokesman Andriy Lysenko said Ukrainian forces had repelled several separatist attacks on the airport in the past 24 hours but "non-stop fighting" continued and "significant numbers of armour, heavy artillery and troops" had moved into the area.