BANGKOK • Thailand's 83-year-old Queen Sirikit has undergone medical tests and has "insufficient blood in the brain", the Royal Household Bureau said in a rare statement on her health.

Her husband, King Bhumibol Adulyadej, 88, is in failing health and is also being treated for various ailments at a Bangkok hospital.

"An X-ray showed that there is still a trace of a former illness of insufficient blood in the brain as per in 2012 but the check found no new abnormalities," the palace said in the statement on the queen.

Queen Sirikit, who has seldom been seen in public in recent years, went for a health check on Wednesday, it said.

The Thai royal succession has prompted worries about instability in a country that has witnessed 19 coups or attempted coups and at least 19 Constitutions since a constitutional monarchy replaced an absolute one in 1932.

News about the royals is tightly controlled in Thailand, where laws protecting the royal family from insult make it a crime to defame, insult or threaten the king, queen, heir to the throne or regent. The palace last released a statement on Queen Sirikit's health in 2014.

REUTERS