BANGKOK, July 22 (Reuters) - Anti-coup protesters clashed with police in Thailand's capital on Sunday during a rally to demand the resignation of a top adviser to the king.

About 5,000 demonstrators marched to the house of Prem Tinsulanonda, chief adviser to King Bhumibol Adulyadej, accusing him of masterminding a coup that removed Prime Minister Thaksin Shinawatra last year.

When anti-riot police tried to disperse the crowd outside Prem's house, the protesters hurled rocks, water bottles and other objects at them.

Another group of protesters scuffled with police blocking a road leading to the former prime minister's home.

"Police are trying to control the situation, but the protesters are harming property," a spokesman for the Council for National Security, as the coup leaders call themselves, told TITV television.

More than 40 people, including some police officers, were taken to hospital with minor head wounds and other injuries, hospital officials said.

"We will keep on fighting," Jakrapob Penkair, a former Thaksin government spokesman who is now a key leader in the Democratic Alliance Against Dictatorship, told Reuters.

"The authorities tried to break up our protest without even trying to talk to us," he said, accusing the police of using tear gas to disperse the crowd.

The stand-off at Prem's home ended when the crowd marched back to a parade ground near Bangkok's glittering Grand Palace where they planned to continue the rally.

At face value, the coup stems from middle-class street protests in 2006 against Thaksin's autocratic style and huge personal wealth, which his opponents say he wielded unfairly to secure unassailable support from rural voters.

But analysts say it was as much about a royalist military and corporate elite removing a nouveau riche, ethnic Chinese businessman who had encroached too far on their traditional turf.

Thaksin was in New York at the time of the coup and has spent most of the interim in London, where he is buying an English football club, or travelling round Asia playing golf and giving interviews and lectures that have unnerved the generals.

Last week, Thaksin sued a military-appointed anti-graft panel for 50 billion baht ($1.5 billion) in compensation for damage caused by its order to freeze $1.58 billion of his assets.