Image copyright AP Image caption The Thai king, seen here in a 2012 photo, is greatly revered in his country

Thailand's King Bhumibol Adulyadej is improving following an operation at a Bangkok hospital to remove his gallbladder, said palace officials.

The 86-year-old king is revered as a near-deity in Thailand and news of his latest illness has sparked concern across the country.

He is often seen as a unifying force in Thailand which has seen political deadlock in recent years.

A stand-off between the government and royalists ended in May with a coup.

Since then, coup leader General Prayuth Chan-ocha has been appointed prime minister, a move which was endorsed by the king.

Mr Prayuth visited the Siriraj Hospital on Monday to sign a book of support for the monarch, said AFP news agency.

'Fever lowered'

A palace statement said surgeons removed the king's gallbladder on Sunday night after it was found to be swollen.

"The operation was satisfactory and His Majesty returned to his room at 20 minutes past midnight. This morning the heartbeat has lowered, blood pressure is normal and His Majesty's fever is lower," the statement said.

Many Thais are praying for the king's health and several showed up at the hospital wearing pink and yellow which are colours associated with the king, reported The Nation.

Image copyright EPA Image caption Many are praying for the king's recovery in Thailand

The king has been admitted to the Siriraj Hospital several times in recent years. He was treated there for stomach inflammation last month.

In 2009 he was admitted for a lung infection, and spent nearly four years living in a special suite in the hospital.