North Korea has accused the head of the International Atomic Energy Agency of taking sides in discussing nuclear activities on the Korea peninsula.

A North Korea foreign ministry spokesman told Pyongyang's official Korean Central News Agency that IAEA chief Mohamed ElBaradei employed a double standard last week when he called North Korea's nuclear development far more serious than revelations South Korean scientists had conducted secret nuclear experiments.

The unnamed spokesman said North Korea cannot overlook what he called the 'irresponsible attitude' of Mr. ElBaradei, who he said was ignoring reality and forgetful of his duty.

South Korea recently admitted its scientists had conducted a plutonium-based nuclear experiment in 1982 and a uranium enrichment experiment in 2000.