By Richard Balmforth
* Bus struck by shell at army checkpoint, says regional spokesman
* Rebels deny they were behind the attack
* Fighting intensifies at Donetsk airport
* Foreign ministers scrap plans for peace summit (Expands with detail on attack, political developments, context)
KIEV, Jan 13 (Reuters) – Shelling hit a passenger bus in eastern Ukraine on Tuesday, killing at least 10 people, and fighting intensified around the international airport in the city of Donetsk as separatists tried to oust government forces.
The bus attack near the town of Volnovakha south of Donetsk, which is the heart of a nine-month-old separatist conflict, further deflated peace hopes after talks between Russia, Ukraine, France and Germany ended without notable progress on Monday. Pro-Russian rebels seized parts of eastern Ukraine after Kiev’s Moscow-backed president was toppled by popular unrest.
