South Korea's Unification Minister Kwon Young-se has criticized North Korea for failing to answer calls on liaison and military hotlines that the two countries use.

North Korea has not responded since Friday to routine calls, which are normally made twice a day. Seoul suspects that this may be intentional.

On Tuesday, Kwon said in a statement that the government "expresses strong regret over North Korea's unilateral and irresponsible attitude, and strongly warns that it will eventually isolate and put itself in a predicament."

The statement also refers to the Kaesong industrial complex, which the two Koreas jointly ran until 2016. It said North Korea is operating facilities there without permission and using the property of South Korean companies.

It said the government strongly condemns such illegal acts, as they violate a bilateral agreement and North Korean law.

South Korean media outlets report this is the first time in 10 years that a unification minister has issued such a statement about North Korea.

Kwon said he released the statement because he wants North Korea to change its actions. He said, "North Korea's move to raise tensions is not good for the Korean Peninsula as well as the North itself."