North Korea indicated Tuesday it may not join next month's Winter Olympics in South Korea, after a conservative group there burned a big picture of North Korean leader Kim Jong Un and the country's national flag.

On Monday, a South Korean conservative organization held a protest rally against North Korea's participation in the Olympics, when a Pyongyang delegation arrived at Seoul central train station.

"We cannot but take a serious consideration of our follow-up measures regarding the (Pyeongchang) Winter Olympics," the Committee for the Peaceful Reunification of the Fatherland said in a statement.

Pyongyang also urged Seoul to swiftly implement steps to prevent the recurrence of such acts.

"We will never tolerate hideous acts of the conservative hooligans who insulted the sacred dignity and symbol of the DPRK," the statement said, using the acronym of North Korea's formal name, the Democratic People's Republic of Korea.

"If the north-south agreement and schedules for the DPRK's participation in the Olympics are cancelled...the blame will wholly rest with the conservative group and the south Korean authorities," the statement added.

In a surprisingly conciliatory gesture to South Korea, North Korea recently announced plans to send 22 athletes as well as 24 coaches and officials to the Olympics that start Feb. 9.

But North Korea has shown no signs of abandoning its nuclear and missile programs.