North and South Korea have exchanged gunshots across their land border, the South’s Yonhap news agency reports. The incident came as South Korean activists launched balloons containing leaflets condemning North Korean leader, Kim Jong-un. Pyongyang had warned of “catastrophic” consequences if Seoul allowed the activists to go ahead. The two sides exchange periodic gunshots across their disputed maritime border but incidents on land are rare. Yonhap, citing military officials, said the North fired towards the balloons and South Korea responded after some shots landed south of the border. There was no immediate information on whether there were any casualties. The clash came as North Korea marked the 69th anniversary of its ruling party. Mr Jon-un, who has not been seen in public for more than a month, did not attend, according to a list provided by state media.