North Korea executed dozens of officials last year, including a top party secretary in charge of agriculture, a former North Korean diplomat said Wednesday.

Kim Dong Su, who defected earlier this month in Italy, said most of those executed were from a youth league linked with the ruling Workers' Party and had been charged with spying.The defector said agriculture secretary Suh Kwan Hee, 72, was among those executed, but it was unclear from his remarks whether Suh had been accused of spying.

"It was the first reliable confirmation of a major political purge carried out under (North Korean leader) Kim Jong Il," said an official of South Korea's main intelligence agency.

Kim did not give an exact figure for the number of people put before firing squads but referred to "dozens" of executions.

Kim was a third secretary in the five-member North Korean mission to the U.N. Food and Agriculture Organization in Rome when he defected on Feb. 4 with his wife and 8-year-old son.

Appearing at a news conference staged by South Korea's intelligence agency, Kim said most of the officials executed were members of a trading company that the youth league runs to earn foreign currency.

He said the case also put in question the future of Chang Sung Taek, 52, a brother-in-law and confidant of Kim Jong Il.

South Korean intelligence officials said Chang, who heads the Organization and Guidance Department in the ruling party, does not appear to have been directly involved in the alleged spy case.

But they noted that Chang's department is responsible for supervising the socialist youth league, which reportedly has millions of members aged between 14 and 30.

Kim served as a diplomat in Europe for more than 10 years before defecting.