Well-wishers gather outside the Chalerm Phrakiart building at Siriraj Hospital, where His Majesty the King is resting after spinal surgery last week, to give moral support to the monarch.

The latest official statement on His Majesty's progress said doctors had advised the King to exercise.

His Majesty was spending time standing up and then walking for periods of about six minutes.

His Majesty was also able to take solid food.

Examinations showed His Majesty's physical recovery was satisfactory.

"After walking, His Majesty's condition remained normal," the statement said.

The 79-year-old monarch underwent lumbar spinal stenosis surgery at Siriraj Hospital on Thursday.

His Majesty was able to sit up in bed and was being asked to switch his reclining positions frequently.

The statement added post-surgery pain was "gradually decreasing".

Khun Ploypailin Jensen, a granddaughter and the eldest child of Princess Ubol Rattana, visited His Majesty and signed a book of get-well wishes.

She is currently training in Hong Kong and will return to Thailand again next week.

Her Royal Highness Princess Maha Chakri Sirindhorn spent more than four hours with the King at the hospital's Chalerm Phrakiart building.

She acknowledged the crowds gathered to greet her and other members of the Royal family.

The building has been packed since Thursday with people coming to sign get-well messages.

Crowds outside the building where His Majesty is resting hail "Long Live the King" whenever a Royal family member appears at a window.

Sultan Ismail Putra and Tuanku Anis of Malaysia's Kelantan state sent a floral bouquet and a message of good will to His Majesty. Many politicians and senior government officials have also signed messages wishing His Majesty a speedy recovery.

As many as 1,000 people ran from Sanam Luang to the hospital yesterday where they then signed the message books.