BANGKOK (Reuters) - Thailand’s main mobile telecoms operators instructed customers on Sunday to report “inappropriate content about the royal institution”, as the government steps up scrutiny for material deemed insulting to the monarchy.

A portrait of Thailand's late King Bhumibol Adulyadej is seen at Sala Chalermkrung Royal Theatre which is closed following the death of the king, in Bangkok, Thailand October 15, 2016. REUTERS/Jorge Silva

King Bhumibol Adulyadej died on Thursday after seven decades on the throne. His son, Crown Prince Maha Vajiralongkorn, is due to become the next king after a period of mourning.

Thailand has a tough law against lese majeste, or insulting the monarchy. Convictions have become more frequent, and punishments more severe, under a military government that seized power in 2014.

Mobile operators Advanced Info Service Pcl (AIS) , Total Access Communication Pcl and True Move, a unit of True Corp, posted instructions on a messaging app and on their Facebook pages, for how to report Facebook posts and Youtube videos.

True said it was following a request from the broadcasting regulator, the National Broadcasting and Telecommunications Commission (NBTC).

“The NBTC has asked all mobile operators to send the instruction to our clients,” Pimolpan Siriwongwan-ngam, True’s head of public relations, told Reuters.

“We’re only acting as channels to spread the message.”

Spokeswomen for AIS and Total Access confirmed they had followed the NBTC guideline.

The operators said people should send URLs or screenshots of websites deemed offensive to the Ministry of Information and Communication Technology and the NBTC.

On Friday, the NBTC said it had asked internet service providers to monitor content and block anything inappropriate.

Operators must also inform platforms such as Facebook, Twitter, Youtube, and messaging apps, to block such content.

The failure of internet providers to block inappropriate content when it is found would be considered a crime, NBCT secretary-general Takorn Tantasith said in a statement.

Information ministry spokesman Chatchai Khunpitiluck said some content hurt the feelings of people grieving for the revered king.

“Many heartbroken Thais are quite sensitive. When they see illegal content that offends them, they’ll be more stressed,” he said. “We have to let them know about channels to report content to relieve their sense of helplessness.”

Chatchai said more people had come across content they deemed inappropriate, partly because more people were going online to read about the king since his death.

Police and the MICT declined to say how many complaints they had received.

The government had a hotline for reporting content, Suwaphan Tanyuvardhana, minister attached to the Prime Minister’s Office, told Reuters. Police said they were intensifying monitoring the internet.