BANGKOK - The sister-in-law of Thailand's Crown Prince has been sentenced to two and a half years in prison, after being found guilty of insulting the monarchy, the Khaosod news website reported.

Sudathip Muangnuan had cited her status as the sister of former princess Srirasmi, the wife of Prince Maha Vajiralongkorn, to sell overpriced food products to the royal palace for the past 12 years, the court found.

According to court papers, Sudathip won the rights to supply the palace with food products like chilli paste, by using her connections to the Royal Family to pressure other competitors to drop out of contract bid.

On Feb 2, judges found her guilty of violating Thailand's lese majeste law, which can be punished with a jail term of up to 15 years.

"The remarks of the defendant were slanderous, laying false claims to and insulting the monarchy," the court briefing read.

"She violated, made false accusations toward, and caused damages to the Royal Majesty."

Sudathip was arrested in Dec 2014 and identified by police as a conspirator in a massive corruption and extortion ring run by high-ranking police officers in the Central Investigation Bureau (CIB).

At least 26 people have been arrested in connection with the alleged crime syndicate. Many of the suspects are related to Srirasmi.

On Jan 30, former police lieutenant-general Kowit Wongrungroj and his commanding officer, former CIB chief Pongpat Chayapan, were sentenced to six years in prison for defaming the Crown Prince and running an illegal casino. The duo are Srirasmi's brother and uncle respectively.

In response to the scandal, Prince Vajiralongkorn stripped Srirasmi's entire family of the royally bestowed surname, forcing them to revert back to their commoner surname last November.

Srirasmi then resigned from her royal status less than two weeks later. She has not been seen in public since.

There has been no official report of a divorce yet between the couple, who married in 2001 and have a nine-year-old son.