A human rights group says their Swedish co-founder has been detained in China on suspicion of endangering state security. Peter Dahlin’s detention comes as China intensifies a crackdown on civil society to snuff out any potential opposition to the ruling Communist Party. China Urgent Action Working Group says 35-year-old Dahlin was detained on January 3 on his way to Beijing’s main airport, where he was due to fly to Thailand via Hong Kong. His Chinese girlfriend has also disappeared. READ MORE: ‘The smog is thick and the night dark’: China charges seven human rights lawyers with subversion The group says Dahlin suffers from a medical condition that needs daily medication. The Swedish Embassy in Beijing confirmed that a 35-year-old citizen had been detained in China and said it was investigating. China has been cracking down on human rights activists, lawyers and bloggers.