Thailand's revered king called on the politically divided nation to unite during a brief public excursion from hospital to mark his 82nd birthday.

King Bhumibol Adulyadej, the world's longest reigning monarch, who is regarded as a demi-god by many Thais, made a rare address at Bangkok's royal palace where dignitaries were gathered for his annual birthday ceremony.

"My well-being can be achieved with our nation's stability, prosperity and peace," he said.

"To achieve these things everyone must determine to perform their duties to their best ability, conscious of their own wisdom and honesty, for the common good above all other interests."

The king thanked his well-wishers and urged those in positions of power to be mindful of their duty to the nation.

"I am deeply thankful to all of you who have offered birthday wishes to me, with such beautiful and sincere words to bring me joy.

"I ask all of you holding important positions in the key institutions of our country to consider thoroughly your duty and make a determination to do your duty to your best ability for success," he said.

The ceremony was attended by members of the royal family, the privy council, Prime Minister Abhisit Vejjajiva and cabinet ministers, other members of parliament and senior members of the judiciary and military.

The king has been a stabilising force during his six politically turbulent decades on the throne but Thailand has been rocked by years of rival political protests that have sometimes turned violent.

The king returned to a Bangkok hospital Saturday after leaving for about one hour, pushed in a wheelchair and wearing the full white royal uniform covered with a gold embroidered gown.

Thousands of Thai people wearing pink for good luck lined the streets to watch the royal motorcade as it passed over Bangkok's Chao Phraya river from Siriraj Hospital to the Grand Palace.

Many waved Thai national flags and royal yellow flags and shouted: "Long live the king."

King Bhumibol was admitted to Bangkok's Siriraj Hospital on September 19 with a lung infection and fever. He has appeared twice in public since then.

Bangkok resident, 74-year-old Thanom Chumpoo, greeted the king outside the hospital and said she had been visiting every day, hoping he would make an appearance.

"I am glad that he is recovered. I am so overwhelmed to see him and want him to live forever to guard us," she told AFP with a beaming smile.

Thaksin supporters put off demonstrations

The birthday of King Bhumibol is marked by a public holiday and celebrated by Thais across the kingdom with fireworks and Buddhist rituals.

But his annual speech on the eve of his birthday was officially postponed by the royal household on Monday, along with a military parade due to be held Wednesday.

His son, Crown Prince Maha Vajiralongkorn, is due to represent his father at weekend Buddhist ceremonies, and will preside over a gathering of diplomats on December 8.

Speaking at Saturday's ceremony, the Crown Prince said he was delighted to see the king in better health.

"I am overwhelmed and rejoice to see the king in good health and recovered from illness," he said in his prepared statement.

Supporters of fugitive former premier Thaksin Shinawatra called off rallies due to start last weekend after the billionaire said the protests were too close to the monarch's birthday.

More than 10 people have been killed and hundreds wounded on Thailand's streets over the past year during separate protest campaigns by friends and foes of Thaksin, who was ousted in a military coup in 2006.

In recent weeks Thai police have charged four people with spreading false rumours on the Internet about the king's health, after concerns over his condition sent stocks plunging.

Thailand has a strict lese majeste law, under which insulting or defaming any member of the royal family is punishable by up to 15 years in jail.

- AFP