The number of North Korean defectors to South Korea tumbled 43 percent in the first five months of 2012 from a year earlier due to increased security along the North Korea-China border, the Seoul government said Sunday.

A total of 610 North Korean defectors arrived in South Korea in the January-May period, down 42.6 percent from the same period last year, according to data from the Unification Ministry, which handles inter-Korean affairs.

The number of arrivals in the January-May period last year reached 1,062, with the full-year total rising to 2,706.

January recorded the largest number of arrivals this year at 160, while February recorded the smallest number at 90, the ministry said. Last year, the number of monthly arrivals surpassed 200 in nine out of 12 months.

"The reason appears to be stronger crackdowns in the North Korea-China border area following the death of (North Korean leader) Kim Jong-il at the end of last year," said a government official who spoke on condition of anonymity.

China has reportedly strengthened crackdowns on North Korean defectors in recent months, after rights groups and lawmakers in South Korea and other countries demanded the Chinese government stop the forced repatriation of North Koreans to their homeland, where they could face harsh punishment and even execution.

North Korean defectors flee their communist homeland in order to avoid political oppression and chronic food shortages. Many of them risk their lives while traveling through China and Southeast Asia in the hopes of resettling in the South, now home to more than 23,500 defectors.

That process often takes several months, making it difficult to determine whether the downward trend in arrivals will continue, the official said. (Yonhap)