A number of what appear to be North Korean propaganda leaflets have been spotted inside South Korea's presidential office Cheong Wa Dae and in nearby areas, the office confirmed Monday, prompting suspicions over how they found their way into the highly secured area.

The small propaganda bills were seen scattered on streets near the presidential office, while some were even found in the yard of Chunchugwan, the Cheong Wa Dae press center that sits on the eastern side of the presidential office, according to Cheong Wa Dae security officials.

North Korean leaflets are not hard to find in South Korea while the communist state is said to periodically send leaflets using balloons and unmanned aerial vehicles, but it marked a rare incident for such bills to be found near the presidential office.

The bills found this week near Cheong Wa Dae carried at least three different phrases, all condemning South Korea or the United States for taking a hostile policy toward Pyongyang.

One, for instance, took pity on Seoul for relying on the United States for its own defense while claiming the US itself was afraid of North Korea.

A Cheong Wa Dae official said an investigation will soon be launched to find out how the leaflets found their way to the presidential office.

"The security team has collected the bills, and related offices will soon investigate how they came to be found in the area," the official said, while speaking on the condition of anonymity. (Yonhap)