Police Col. Weerawit Chanchamroen said the explosion took place shortly after midnight near the Royal Turf Club, which is one of Bangkok’s two racetracks. He said the homemade bomb did not completely detonate and caused only minor damage to the club gate and a pedestrian bridge.

Weerawit said authorities are still investigating the motive for the attack.

Dozens of bombings have plagued the capital this year in tandem with anti-government protests by supporters of former Prime Minister Thaksin Shinawatra, who was ousted in a 2006 military coup. At least a half dozen grenades have exploded since July at targets connected with the government, killing one person and wounding a dozen more. There have been no claims of responsibility, though the government has suggested the attacks are part of an anti-government conspiracy.

There were two other small bombings Friday in Bangkok, but the targets had no political significance and police said they appeared to be related to personal or business disputes.

However, the Royal Turf Club, popularly known as the Nang Lerng race track, is closely associated with Thailand’s traditional power holders in the royal palace and the military. Thaksin’s supporters, as well as pro-democracy activists, accuse the ruling elite of staging the 2006 coup because they felt his popularity and power threatened their own influence.

According to Paul Handley, author of the 2006 book “The King Never Smiles: A Biography of Thailand’s King Bhumibol Adulyadej,” the Royal Turf Club and its crosstown counterpart, the Royal Bangkok Sports Club, both serve as exclusive sports, golf and horse racing clubs for the rich, the titled and the powerful.

“At both as well, untaxed backroom betting operations on horse races dwarfed the official tote, while enriching club management and membership, invariably the aristocratic and military elite,” Handley wrote in his book, which is banned in Thailand.

In 2002, when Thaksin was prime minister, his cousin, then-assistant army chief Gen. Chaisit Shinawatra, led an attempt to gain control of the Royal Turf Club through election to its board.

The takeover bid was defeated by an incumbent team led by veteran politician Sanan Kachornprasart, former secretary general of the Democrat Party, Thaksin’s main political rivals, wrote Wassana Nanuam, the military correspondent for the Bangkok Post newspaper.

Although Sanan is now chief adviser to the Chart Thai Pattana Party, he remains close to the Democrats ands serves as a deputy prime minister in the Democrat-led government of Prime Minister Abhisit Vejjajiva. Last week, the Thai press was abuzz with speculation that Sanan could take over as prime minister if a court ruling on alleged election law violations forces Abhisit from his job.