North Korea's premier was relieved of his position Monday for health reasons and resigned from the ruling Politburo, the country's official news agency said.

The Korean Central News Agency report, monitored in Tokyo, said Premier Li Gun Mo will be replaced by Yon Hyong Muk, a Politburo member and secretary of the Korean Workers' (Communist) Party.It said the changes were approved at an extraordinary session of the Supreme People's Assembly.

Li had been premier since Dec. 29, 1986. Little is known about him.

On Saturday, KCNA reported that the communist party's 15-member standing committee had requested an extraordinary meeting of the assembly. That prompted speculation the party could have important decisions to be approved by the congress.

Another official report, from Radio Pyongyang, said a son of party leader Kim Il Sung, Kim Pyong Il, was appointed ambassador to Bulgaria.

Kim Pyong Il became ambassador to Hungary in August but returned to North Korea in September to protest Hungary's agreement with South Korea to exchange permanent trade offices in their capital cities.

Kim Pyong Il was director-general of North Korea's People's Armed Forces Bureau prior to his appointment as ambassador to Hungary.

The appointment of a new ambassador to Hungary was not announced, according to Radio Press, a Japanese news agency that monitors communist bloc broadcasts.

North Korea is believed to have downgraded its relations with Hungary to one requiring the exchange of deputy ambassadors, Radio Press said.