Six Thailand nationals, arrestedfor violating their visa norms and were undergoing treatment for coronavirus at a government hospital near here after testing positive for it have recovered and been discharged, police said on Tuesday.They were shifted to Puzhal prison in Chennai after being discharged from the Perundurai IRT Government Medical College Hospital in the district.All the six were shifted to Puzhal prison on Monday night with police security, they said.The arrest was effected at the hospital days after cases were registered against them under relevant sections of IPC.Police personnel were posted outside the isolation ward of the hospital.The action was taken based on a complaint by local Tahsildar lodged with the police.The Thai Nationals, who possessed tourist visas engaged themselves in Islamic preaching despite suffering from COVID- 19, police said.In all, a group of seven Thailand nationals came here some three weeks ago, stayed at Kollampalayam Housing Unit complex and engaged themselves in preaching.One among them died due to kidney ailment at a government hospital in Coimbatore. The remaining six tested positive for coronavirus, prompting authorities to launch a massive contact tracing of those who had attended the preaching sessions and others.