King Bhumibol Adulyadej had "experienced intermittent twitching of his right hand and his heart beat was slightly increased last night.
An X-ray computerised tomography of his brain revealed that there was minute subdural bleeding in the left frontal area. After medication was given intravenously last night the seizure disappeared," a statement issued by the royal palace said.
It said that doctors urged him not to take on any duties for a while.
Doctors said that after the medication the king's right hand movement, heart beat and pressure were normal.
The king had been scheduled to visit a development project on Sunday in the western province of Ratchaburi.
The king was admitted to the hospital in September 2009 after suffering respiratory problems.
