BANGKOK - Thailand's King Bhumibol Adulyadej, the world's longest-reigning monarch, was readmitted to a Bangkok hospital late on Friday after leaving it last month, the palace said in an announcement on Saturday.
The 86-year-old king has been admitted for a high fever and the diagnosis suggested blood infection, so doctors had asked him to stay at Siriraj hospital for special treatment, the Bureau of the Royal Household said in a statement.
It said that after taking medicine, the king's blood pressure had stabilized and his fever had decreased. His condition was steadily improving, the statement added.
The statement gave no details on how long the king was expected to stay in hospital.
On Sept. 15, the king left hospital after more than a month of treatment for stomach inflammation.
That followed his stay of nearly four years from 2009 to 2013 at the same hospital, where he was treated for a range of illnesses.
He has rarely been seen in public since leaving the hospital in 2013 and lives at the Klai Kangwon Palace - which translates as "Far from Worries Palace" - in the seaside town of Hua Hin, south of Bangkok.
The king, a constitutional monarch, is revered by many Thais.
He has stayed silent during Thailand's latest crisis which began in November with opposition groups taking to the streets in a bid to remove Prime Minister Yingluck Shinawatra from office and culminated in the bloodless May 22 military coup.
He made several interventions in the 1970s and 1990s to call for calm during political crises.
The latest round of tumult began in 2005 and broadly pits supporters and allies of billionaire former Prime Minister Thaksin Shinawatra, Yingluck's brother, against a military-backed royalist elite that despises him and has accused him of disrespect to the monarchy.
Thaksin has repeatedly pledged his allegiance to the king, dismissing the accusations as a smear campaign by his powerful enemies to discredit him. He has lived in self-imposed exile since 2008 to avoid a jail term handed down for graft.
Thailand has harsh laws designed to protect the monarchy. Those found guilty of insulting the royal family can serve up to 15 years in prison for each offence.