A senior security official at the presidential office has been sacked only a week after his appointment, an official said Wednesday, a highly unusual decision that has sparked speculation that he had conflicts with other officials over how to deal with North Korea.

Chun Hae-sung, a senior unification ministry official who was named last week as the presidential secretary for security strategy under the office of national security, has been sent back to his ministry, presidential spokesman Min Kyung-wook said.

Min said Chun has been replaced due to concerns that he is very important to the unification ministry and his absence could affect its operations. Unification Minister Ryoo Kihl-jae also strongly requested that Chun return to the ministry, the spokesman said.

"I've heard the unification ministry's position has been taken into consideration," he said.

But many found the explanations hard to buy.

The announcement of Chun's departure came a day after South Korea announced that it agreed to hold its first high-level talks with North Korea in seven years on Wednesday. That has raised speculation that Chun and other security officials clashed over how to handle North Korea's offer of rare high-level talks.

Chun is considered a soft-line official favoring dialogue with Pyongyang.

The spokesman said that Cheon Seong-whun, a security expert who heads the state-run Korea Institute for National Unification think tank, has been chosen to replace Chun because he has "ample knowledge and experience with regard to unification." (Yonhap News)