Police on Thursday raided the office of a vocal North Korean defector who claimed to have sent anti-Pyongyang propaganda leaflets into the North in defiance of a ban.
  
Police launched an investigation after Park Sang-hak, head of Fighters for a Free North Korea, a North Korean defectors group, claimed Friday that his organization sent 10 balloons carrying around 500,000 leaflets between April 25-29.
  
The raid on his office took place until afternoon with investigators securing documents and other materials needed for the probe into the case, officials said.
  
"We will analyze the secured materials, while also seeking to summon people involved in the matter," an official said. "We will carry out a swift and stern investigation."
  
If confirmed, Park's group will be the first to have sent the leaflets critical of the Kim Jong-un regime since Seoul banned such activity under a revised law in March.
  
Violations of the law are punishable by up to three years in prison or up to 30 million won (US$27,000) in fines.
  
On Sunday, Kim Yo-jong, the sister of North Korean leader Kim Jong-un, issued a statement slamming South Korea for failing to stop the defector group from sending the leaflets, threatening to take "corresponding action" in response to the "intolerable provocation." (Yonhap)