SEOUL, South Korea — Young North Korean leader Kim Jong Un has executed 70 officials since taking power in late 2011 in a “reign of terror” that far exceeds the bloodshed of his dictator father’s early rule, South Korean officials said Thursday.

South Korean Foreign Minister Yun Byung-se, at a forum in Seoul, compared Kim Jong Un’s 70 executions with those of his late father, Kim Jong Il, who he said executed about 10 officials during his first years in power.

An official from South Korea’s National Intelligence Service, who refused to be named, citing office rules, confirmed that the spy agency believes the younger Kim has executed about 70 officials but wouldn’t reveal how it obtained the information.

Yun also said that the younger Kim’s “reign of terror affects significantly” North Koreans working overseas by inspiring them to defect to the South, but he also didn’t reveal how he got the details.

North Korea, an authoritarian nation ruled by the Kim family since its founding in 1948, is secretive about its government’s inner workings, and information collected by outsiders is often impossible to confirm.