A 62-year-old Thai man serving one of the longest jail terms given under laws protecting the royal family from insults died in custody today after complaining of stomach pain, a prison official said.

Ampol Tangnoppakul died at 9 a.m. at the government-run Klang Hospital, Suchart Wong-ananchai, director-general of the Department of Corrections, told reporters in Bangkok. In November a court sentenced him to 20 years in prison for sending text messages that threatened and defamed Queen Sirikit, 79.

“Grandfather died,” Arnon Numpa, Ampol’s lawyer, wrote on his Facebook page. “Please accompany him at the prison.”

Ampol’s sentence prompted the U.S., European Union and United Nations to issue statements calling on Thailand to respect freedom of speech. The Southeast Asian country has seen a surge in the number of cases alleging insults against the royal family in recent years, coinciding with political violence since a 2006 coup.

Ampol, who pleaded not guilty, was convicted of sending four messages in May to the mobile phone of an aide to former Prime Minister Abhisit Vejjajiva, the court said. It rejected a defense argument that his phone was being repaired at the time.

Dubbed “Uncle SMS” by the local media, Ampol was admitted to the Medical Correctional Institution last week because of a stomach pain, Arnon said. It wasn’t clear when he was moved to Klang Hospital.

‘Chilling Effect’

Thailand’s lese majeste law mandates jail sentences as long as 15 years per charge for defaming, insulting or threatening the king, queen, heir apparent or regent. The UN human rights office in December said the law had a “chilling effect” on free speech and called for it to be amended.

The number of lese-majeste cases before Thailand’s lower courts increased to 478 in 2010 from 33 in 2005, a year before the coup that ousted former Prime Minister Thaksin Shinawatra, according to statistics compiled by the Campaign Committee for the Amendment of Article 112, which is pushing to change the law.

The lese-majeste law “is not aimed at curbing people’s rights to freedom of opinion and expression nor the legitimate exercise of academic freedom, including debates about the monarchy as an institution,” Thani Thongphakdi, foreign ministry spokesman, said in a Dec. 14 statement. Ampol was accorded “due process,” he said.

Thailand’s military has accused Thaksin and his supporters of undermining King Bhumibol Adulyadej, 84, who took the throne in 1946. A royal anthem paying homage to the king is played before movies screened at theaters in Thailand and a nightly news show focused on the monarchy is broadcast throughout the country.

To contact the reporter on this story: Supunnabul Suwannakij in Bangkok at ssuwannakij@bloomberg.net

To contact the editor responsible for this story: Peter Hirschberg at phirschberg@bloomberg.net