Thailand's King Bhumibol Adulyadej delivers his birthday speech at the Klai Kangwon Palace, Hua Hin, Prachuap Khiri Khan province Dec 5, 2013, in this handout photograph provided by the Royal Palace.  [Photo/Agencies]

BANGKOK - Thai King Bhumibol Adulyadej called on his people to do their duty for the good of the country in a birthday address on Thursday, but avoided direct reference to the latest political turmoil roiling the capital.

Protesters are attempting to bring down the government of Prime Minister Yingluck Shinawatra and five people have been killed in clashes over the past week. The two sides reached a truce to mark the king's birthday.

The 86-year-old king is the only monarch most Thais have ever known and has been a father figure who has defused previous crises. His words were awaited with expectation.

The world's longest-reigning monarch, who left hospital in July after a four-year stay, looked sombre and spoke slowly, pausing at times, as he read out his address.

He referred to people doing their duty to support each other.

"All Thais should realise this point a lot and behave and perform our duties accordingly, our duty for the sake of the public, for stability, security for our nation of Thailand," the king told a gathering of the country's top leaders.

The birthday ceremony was held at the king's seaside palace in Hua Hin, about 190 km (118 miles) south of Bangkok, where he moved with Queen Sirikit when he left hospital.

Among those in attendance in formal suits and dress uniforms was the prime minister, the heads of the armed forces and police, top bureaucrats and the leader of the opposition. The queen, who suffered a stroke in July last year, was not seen in television pictures.

The prime minister paid her respects and Crown Prince Vajiralongkorn offered his father birthday wishes and promised to fulfil the king's wishes.

The protests in Bangkok are the latest eruption of a conflict that pits the Bangkok-based royalist establishment against mostly poorer Thais loyal to Yingluck and her brother, former premier Thaksin Shinawatra, who was toppled by the military in 2006 and lives in self-imposed exile.

The establishment and urban middle class have accused Thaksin of undermining the monarchy, which he denies.

Thaksin's largely rural supporters swept his sister to power in 2011 election and there's little doubt she would win again if she were to dissolve parliament and call a snap election, which she has declined to do.