Five people have been arrested on lese majeste charges since his Majesty the King's passing, deputy national police chief Srivara Ransibrahmanakul said Thursday.
Most concern messages posted online which breach Section 112 of the Criminal Code, better known as the lese majeste law, he said. No further details of who had been arrested or where were available. As for similar cases committed by suspects overseas, the police were working with public prosecutors handling international criminal cases, he said.
The deputy national police chief also warned netizens against posts which defame the royal institution.
Meanwhile, What Tingsamitr, chairman of the National Human Rights Commission (NHRC), warned loyalist Thais against acts of vigilantism, saying attacking people who express views critical of the monarchy could breach their rights.
In recent days, several incidents have stirred conflict with members of the public attacking those who allegedly criticise the monarchy in Phuket, Surat Thani and Phangnga.
The latest incident took place in Bangkok on Monday, when a 55-year-old woman, who was said to have made insulting comments about the monarchy on a public bus, was slapped in the face by another woman. The victim reportedly suffered from a mental illness.
In another incident, a man in Chon Buri was beaten and forced to prostrate himself in front of a portrait of His Majesty the King after being accused of posting an inappropriate message concerning the King.
No civilians have the right to use violence against anyone else and should complain to law enforcement authorities about instances of lese majeste, said Mr What.
Government spokesman Sansern Kaewkamnerd said Thais should try to keep the peace during this period of mourning.
Most people were still grieving over the loss of His Majesty the King and the country needs unity and understanding at this difficult time, said Lt Gen Sansern.
"The prime minister understands the feelings of the people unfailingly loyal to the monarchy. But everyone has to be reminded that the monarchy must not be dragged into any conflicts," he said.
"The government won't avoid enforcing the law in cases of proved violations [of the lese majeste law]. Please let the law enforcement authorities do their jobs," Lt Gen Sansern said.
He also warned the public against getting involved in attempts to disseminate information, images, audios or videos that may incite public frustration or conflicts. That would only damage Thailand's reputation and might lead to the wrong perception about Thailand among other nations, he said.
"Spreading news and images in an insensitive manner happens frequently on social media and results in frustrations, misunderstanding and chaos," he said, adding one recent example concerned false news reports about a bomb attack alarm, claimed to have been issued by the 1st Cavalry Squadron.