The 79-year old Thailand King Bhumibol Adulyadej was admitted to Bangkok's Siriraj Hospital Saturday, the Royal Household announced in a statement.

He is under treatment after showing symptoms of loss of strength in the right side of his body and the doctors said he is suffering of a inadequate blood flow to the brain.

The Royal Household announced that after eight hours of drugs administrations, the King Bhumibol Adulyadej is feeling better and he regained strength over his right leg.  He will remain in the hospital for monitoring.

Thailand’s King Bhumibol Adulyadej, who turns 80 on December 5, is the world’s longest reining monarch and last year he celebrated his 60th year on the throne.

He is a constitutional monarch, with the right to veto bills and appointments as head of state, but he is considered as a unifying figure in Thailand.

In the past years, the Thailand king was treated for heart problems and he underwent a hernia operation in 2003 and spinal surgery in July this year.

On Sunday the Thai television announced that hundreds of people have gathered in front of the Siriraj Hospital wearing yellow shirts (the monarchy colour) to wish him a speedy recovery.

The Thai king was visited in the hospital by his wife, Queen Sirikit, and by other top officials.