A North Korean newspaper warns Japan not to increase sanctions for the government's failure to finish an investigation of abductions that occurred 30 years ago.

North Korea agreed to conclude by this fall a new investigation of its kidnapping of Japanese nationals in the 1970s and '80s to use for training spies, South Korea's Yonhap news agency reported Monday.

In return for the reinvestigation, Japan promised to partially lift sanctions it imposed on North Korea after the country conducted an underground nuclear test in 2006.

Late last month Japanese Prime Minister Taro Aso suggested Tokyo might consider additional sanctions.

"Japan's attempt to handle our republic by putting more pressure or imposing additional sanctions itself is nonsense," said a commentary in the newspaper Rodong Sinmun, North Korea's most influential newspaper.

The organ of the Worker's Party said North Korea has a "self-reliant national economy despite the persistent sanction."