The head office of a pro-Pyongyang Korean residents' group in Japan received a call from a man over the weekend who threatened to shoot at the office as well as students of Korean schools in Japan, sources close to the group said Monday.

The caller telephoned the head office of the General Association of Korean Residents in Japan (Chongryun) in Tokyo on Saturday evening, identifying himself as the person who had earlier sent bullets to Chongryun and to the Social Democratic Party, the sources said.

Chongryun consulted the Metropolitan Police Department about the call the same day. Police are investigating what they consider a case of intimidation, and are looking into possible links with the bullet delivery, according to the sources.

On Nov. 9, the head offices of Chongryun and the SDP, both in Tokyo's Chiyoda Ward, each received a threatening letter containing bullets. The letters ordered the groups "to get out of Japan" and "to immediately disband."

On Saturday, the caller demanded Chongryun retract a statement made last week by its vice chairman, Nam Sung U, claiming the group was not involved in the abduction of Japanese nationals in the late 1970s and early 1980s, the sources said.

"Take back the comments made at the news conference," the caller was quoted as saying. "Otherwise, we will shoot bullets at the head office. We will target students of Korean schools."

"Chongryun, as a group, has never involved itself" with the abductions, Nam told a news conference on Nov. 13, referring to the recent admission by Pyongyang that it had abducted or lured 13 Japanese to North Korea in the past.

Chongryun had long maintained that North Korea had not abducted any Japanese.

Police are investigating the bullet incidents, considering them weapons law violations.