Seoul, Jun 30 (IANS): Police in South Korea on Tuesday called in North Korean defector brothers over their groups' anti-Pyongyang leaflet campaign.

Park Sang-hak, head of Fighters for a Free North Korea, and his younger brother Jung-oh, who leads another defector group, Kuensaem, showed up for questioning at the Seoul Metropolitan Police Agency at 9.20 a.m., reports Yonhap News Agency

Defying the government's warning against leafleting, Park claimed that his group sent some 500,000 leaflets carried by 20 large helium balloons over to the North last week.

The South Korean presidential office earlier warned that the government would crack down on such acts, which it said constitute a violation of laws including the inter-Korean exchange and cooperation act.

On June 10, the Unification Ministry filed a criminal complaint with police against the two organizations and decided to revoke their business permits.

The campaign to scatter leaflets that criticize the North Korean political system and the North's ruling Kim family has recently been a major source of confrontation between the two Koreas.

Police plan to question the brothers on various suspicions raised against their activist groups that have been leading the leaflet campaign.

Last week, police raided the offices of the two defector groups, said the Yonhap News Agency report.

They have also been probing into the case by interviewing residents in the border towns of Gimpo, Paju and Yeoncheon in Gyeonggi Province and Gangwha in Incheon, west of Seoul.

Police are expected to decide whether to push for their indictment following the questioning.