BANGKOK (Reuters) - Thailand's King Bhumibol Adulyadej, the world's longest-reigning monarch, was discharged on Monday in what the palace said was a healthy condition after nearly five weeks of treatment at a Bangkok hospital for stomach inflammation.

Accompanied by Queen Sirikit, who was also admitted for a health check-up, the King was greeted by thousands of Thais who cheered and waved flags outside Siriraj hospital, where he had stayed for nearly four years from 2009 to 2013.

The King and Queen - aged 86 and 82 respectively - headed to their palace, Klai Kangwon ("Far from Worries") in the seaside town of Hua Hin south of the capital.

The King was healthy, Mr Distorn Watcharothai, an official of the bureau of the Royal Household, told reporters on Sunday, but gave no further details on the condition of the royal couple.

King Bhumibol remains a figure of national unity revered by Thais as a moral arbiter through decades of upheaval, despite being a constitutional monarch seen as above the political fray.

Despite several interventions in the 1970s and 1990s to call for calm during political crises, he has stayed silent during the seemingly intractable power struggles of recent years.

The latest round of tumult began in 2005 and broadly pits supporters and allies of billionaire former prime minister Thaksin Shinawatra against a military-backed conservative elite that despises him and accuses him of disrespect to the monarchy.

Thaksin vehemently denies that, and has repeatedly pledged his allegiance to the King, dismissing the accusations as a smear campaign by his powerful enemies to discredit him.