A United Nations expert on freedom of speech is urging Thailand to amend controversial laws that prohibit defamation of the country's royal family.

The statement by Frank La Rue on Monday said the legislation encourages self-censorship and stifles important debates on matters of public interest. He added that the laws are overly broad and do not conform with the country's international human rights obligations.

The statement was issued on the same day US citizen Joe Gordon pleaded guilty in Bangkok's Criminal Court to charges of insulting the monarchy, an offense that could be punishable by up to 15 years in prison.

The 55-year-old resident of Colorado was arrested in May while vacationing in Thailand. Gordon, who was born in Thailand, is charged with posting material deemed offensive to the royal family on his blog, as well as a link to a translation of a banned book, while he was living in the U.S.

Speaking to reporters on Monday, Gordon said that he did not want to fight the case, but that he hoped for help from the American government.