North Korea has killed 15 senior officials this year, two South Korean lawmakers said, in the latest public executions in the communist country.

The lawmakers told reporters after being briefed by South Korea's spy agency in a closed-door parliamentary session that in January, a vice forestry minister was executed for allegedly complaining about the country's forestation plan.

North Korea has often carried out public executions in what critics say is aimed at instituting a reign of terror to consolidate North Korean leader Kim Jong-un's grip on power that he inherited upon the death of his father and long-time leader Kim Jong-il in 2011.