* Police operation involves 15,000 officers; 100 protesters arrested
* First of five sites reclaimed from protesters, police say
* "Reforms will benefit your children, too," protest leader tells police (Updates with police clearing demonstrators near Energy Ministry)
By Panarat Thepgumpanat
BANGKOK, Feb 18 (Reuters) - Thai police cleared anti-government protesters on Tuesday from a site near the Energy Ministry in Bangkok that had been occupied for weeks, and officers with shields also confronted demonstrators blocking the government's headquarters.
The protesters have been rallying since November in a bid to oust Prime Minister Yingluck Shinawatra, whom they view as a proxy for her elder brother, Thaksin Shinawatra, a former premier and telecoms tycoon toppled in a military coup in 2006.
Security officials said 15,000 officers were involved in an operation, called the "Peace for Bangkok Mission", to reclaim protest sites around government buildings in the centre and north of the capital.
"We have taken back one of five protest sites that we aimed to reclaim, which is the Ministry of Energy," National Security Council Chief Paradorn Pattanathabutr told Reuters.
"We also arrested around 100 protesters," he said.
The protests are the latest instalment of an eight-year political battle broadly pitting the Bangkok middle class and royalist establishment against the poorer, mostly rural supporters of Yingluck and her billionaire brother Thaksin.
Demonstrators accuse Thaksin of nepotism and corruption and say he used taxpayers' money for populist subsidies and easy loans that have bought him the loyalty of millions in the populous north and northeast.
Yingluck has been forced to abandon her office in Government House by the protesters, who have also blocked major intersections since mid-January.
Bluesky TV, the protest movement's television channel that broadcasts the fiery speeches of leader Suthep Thaugsuban, showed live pictures of ranks of riot police near Government House in central Bangkok.
"We are not fighting to get power for ourselves," Suthep said in address to police lines near Government House.
"The reforms we will set in motion will benefit your children and grandchildren, too. The only enemy of the people is the Thaksin regime," he said.
Demonstrators were massed a few hundred metres away, the two sides separated by sandbag barriers constructed by the protesters. There were no clashes, and footage showed police negotiating with protest leaders.
Labour Minister Chalerm Yoobamrung, who is in charge of the security operation, has said police would also reclaim sites near Government House, the Interior Ministry, and a government administration complex in north Bangkok.
The largest protest sites in the city's business and shopping districts are not included for now. (Addtional reporting by Apornrath Phoonphongphiphat; Writing by Alex Richardson; Editing by Alan Raybould and Paul Tait)