South Korea spy agency under scrutiny after reporting Pyongyang execution

SEOUL (Reuters) - The South Korean spy agency's assertion that North Korea purged its defence chief and executed him with anti-aircraft fire is one of its boldest claims ever, and, given the agency's chequered history, has come under growing scrutiny.

South Korea's National Intelligence Service (NIS) has a daunting major task - to look into arch-enemy North Korea, one of the world's most insular and hostile nations, and find out what's happening in its corridors of power.