SEOUL (Reuters) – Two North Korean defector-run groups targeted for legal action by South Korean authorities say they intend to continue sending propaganda leaflets and humanitarian aid into North Korea, despite criticism from governments in both countries.

South Korea, which is trying to improve ties with the North, on Wednesday accused the two groups, Kuensaem Education Center and Fighters for a Free North Korea, of violating the Inter-Korean Exchange and Co-operation Act by sending leaflets and aid such as rice and medicine.

On Thursday, the South’s Unification Ministry said it had asked Seoul police to investigate the groups.

For the past week, North Korean state media have carried a series of reports and statements from senior officials expressing outrage over defectors, denouncing them as “mongrel dogs” and “human scum little short of wild animals”.

Park Jung-oh, who defected to South Korea in 2000 and heads Kuensaem, said the organisation is still planning to send hundreds of bottles stuffed with rice, medicine and medical face masks to North Korea by throwing them into the sea near the border next week.

Fighters for a Free North Korea, which is run by Park’s brother Park Sang-hak, has also said it plans to send more leaflets into North Korea by balloon over the heavily fortified border.

South Korean authorities have occasionally moved to stop such operations, including in 2018 during a series of summits between South Korean President Moon Jae-in and North Korean leader Kim Jong Un.

The two Koreas even traded fire in 2014 after the North’s military fired machine guns at balloons launched by defector activists.

This week, the ministry said it was considering a law to ban the leaflets and aid, saying they raise tensions with North Korea, pose risks to South Koreans living near the border, and cause environmental damage.

South Korean residents near the border have complained about the two defector groups and they had failed to register the goods before sending them to the North, the ministry said when asked why they had been singled out from around a dozen groups which send goods over the border.

Over the weekend some locals stopped an effort by a separate group to send bottles of rice by sea.

In a poll released on Thursday by South Korean pollster Realmeter, 50% of those surveyed said they would support a ban on such operations, while 41% said they were opposed.

Heo Kwang-il, head of the defector-run Committee for the Democratization of North Korea, said defector groups had been doing work the Moon administration was failing to do to support human rights in North Korea.

U.S.-based Human Rights Watch (HRW) called the leaflets a “relatively harmless expressive act” that should not be banned.

“It is shameful how President Moon and his government are totally unwilling to stand up for the rights of North Koreans,” Phil Robertson, deputy Asia director for HRW said in a statement.

Engagement with North Korea should incorporate South Korean values of democracy and freedom of expression, said Sokeel Park of Liberty in North Korea, which supports defectors.

“Ditching such hard-won values to comply with harsh threats from Pyongyang, just to preserve a veneer of improved inter-Korean relations, sets a terrible precedent and puts all future engagement efforts on a tenuous footing,” he said.