Prime Minister Prayut Chan-O- cha will make the first visit of a Thai leader to Saudi Arabia in more than 30 years after decades of diplomatic tension sparked by a jewel theft from a Saudi palace.
In 1989, Thai-born janitor Kriangkrai Techamong stole $20 million worth of precious gems from the home of a Saudi prince, triggering a feud between the countries dubbed the Blue Diamond Affair that has yet to be resolved.
Thai police later returned some of the jewels but Saudi officials claimed most of the gems were fakes, while the whereabouts of a rare 50-carat blue diamond remains unknown.
The invitation to Prayut for a two-day visit on Tuesday was issued by Saudi Crown Prince Mohammed bin Salman, the Thai government said in a statement.
The statement said that this visit was the first visit by a head of government between the two countries in more than 30 years.
Prayut will meet with the Saudi crown prince to promote bilateral relations, it added.
The Saudi government said in a statement posted on the kingdom's news agency that it had come after consultations that resulted in convergence of views on many issues of common concern.
Saudi Arabia accuses Thai police of bungling their investigation into the theft, with allegations that the stolen gems were taken by senior officers.
Riyadh sent a businessman to investigate in 1990, but he disappeared in Bangkok days after three Saudi diplomats were shot dead in the city.
A case against five men, including a Thai policeman, was dropped in 2014 due to a lack of evidence.
Saudi Arabia hasn't sent an ambassador to Thailand for decades and restricts travel between the countries.
Thailand has tried to patch up ties in order to boost its tourism industry and widen job opportunities for Thai labourers overseas.
Kriangkrai spent five years in jail over the jewel theft and sold most of the gems before his arrest. In 2016 he became a monk.
He said he turned to religion in an attempt to escape bad karma.