Thailand’s King Bhumibol Adulyadej made his first public appearance in over a month since he was taken to hospital, easing fears over the deteriorating health condition of the revered monarch.

Hundreds of well-wishers gathered at Siriraj hospital in the country’s capital, Bangkok, to pay their respects to the 81-year-old king, the world’s longest-reigning monarch.

Looking frail in a cushioned wheelchair and attended by a team of royal physicians, the king was pushed trough a crowd of well-wishers gathering on the floor, chanting "long live the king" as his wheelchair passed through.

“Thais throughout the entire country are overjoyed today to see their beloved king,” said Nelson Rand, FRANCE 24's correspondent in Bangkok.

“There were hundreds of people there to wish him well. They were not expecting him,” said Rand.

The king has been treated in hospital for a lung infection, fever and a loss of appetite, since September 19.

News of his illness sparked a steep fall in the Bangkok stock market and sent the local currency, the Baht, plummeting.

“The general condition of the king is stable. He has gained strength and can eat and sleep as normal, but the team of royal physicians continues to administer antibiotics,” the Royal Household Bureau said in a statement.

In largely Buddhist Thailand, many see the king as a demi-god. His health is a sensitive issue and a cause of major concern in this country of 67 million, the vast majority of whom have only experienced his 63-year reign. 

The monarch is increasingly seen as the only unifying force in a country torn by growing political divisions since the 2006 ouster of then-Prime Minister Thaksin Shinawatra.