South Korea said Wednesday it is closely monitoring the whereabouts of a ranking North Korean official dealing with inter-Korean affairs amid a local media report that he might have been purged.

Won Tong-yon, the vice head of the United Front Department of the Workers' Party, is believed to have been purged and forced to undergo "revolutionary education," a kind of punishment handed down to North Korean officials who commit wrongdoing, under which they must perform hard labor, according to a media report.

Won, a veteran official handling inter-Korean affairs, represented the North's delegation during high-level talks with South Korea held in February 2014.

"We are keeping close tabs on whether something might happen to Won," said an intelligence official, asking not to be named.

If confirmed, the case would be the latest in a series of purges and executions ordered by North Korean leader Kim Jong-un, who is tightening his grip on power through a so-called reign of terror.

The report said that North Korean officials handling inter-Korean affairs, including Won, had to undergo an investigation by the North's authorities over a memoir written by former South Korean President Lee Myung-bak.

In February, Lee published his book detailing his 2008-2013 presidency, in which he claimed the North had proposed summit talks several times, demanding $10 billion and humanitarian aid in return. Lee said he had spurned the offers.

At that time, North Korea accused Lee of malignantly hurting the North's regime, insisting that his book is "peppered with lies."

"The rumor about Won being purged has not been confirmed," said a government official.

Jeong Joon-hee, spokesman at the Unification Ministry, said at a regular press briefing that the ministry cannot officially confirm intelligence about North Korea.

South Korea's spy agency earlier said that the North Korean leader has tightened his grip on his power base in a brutal way, including the execution of about 70 senior officials, including the North's former defense chief, Hyon Yong-chol. (Yonhap)