KUALA LUMPUR - Malaysian Prime Minister Anwar Ibrahim on Wednesday said Brunei's sultan was "stable and in good condition" after he and his wife visited the monarch in hospital.
"Praise be to God, His Majesty's condition is reported to be stable and in good condition. Anwar said in a media statement.
"However, His Majesty still needs monitoring by the medical team."
Sultan Hassanal Bolkiah was admitted to hospital in Kuala Lumpur on Tuesday due to fatigue, though his office insisted the world's longest-serving monarch was in "good health".
The sultan was in Kuala Lumpur with other Association of Southeast Asian Nations (ASEAN) leaders, who on Tuesday met with Chinese Premier Li Qiang and dignitaries from the Gulf Cooperation Council (GCC).
Anwar said doctors have advised the sultan not to accept any visitors for the time being, except from the royal family.
The sultan's office on Tuesday said he had been feeling tired and that Malaysian health experts had advised him to rest for a few days at the National Heart Institute.
Sultan Hassanal ascended the throne in 1967.
He is one of the richest people on the planet, and comes from a family that has ruled Brunei, a small Muslim nation perched on the north of the tropical island of Borneo, for more than 600 years.
His decades ruling Brunei have seen the country gain full independence from Britain and living standards soar to among the highest globally.
But his reign has also been marked by controversies including the introduction of tough Islamic laws legislating penalties such as severing of limbs and death by stoning.