* EU's first major army operation in six years
* U.N. official has warned of risk of genocide
* EU force of up to 1,000 start to arrive by end-February
By Adrian Croft
BRUSSELS, Jan 17 (Reuters) - European Union foreign ministers are expected to agree on Monday to send up to 1,000 soldiers to help stabilise Central African Republic, the EU's first major army operation in six years, EU ...