Thai police have arrested a prominent anti-coup activist for violating an order to report to the ruling junta.

Sombat Boonngamanong, who led an online campaign organising rallies against the coup, was arrested late on Thursday in the eastern Chonburi province.

Military spokeswoman Sirichan Ngathong said an army team had tracked down Mr Sombat through the internet.

Mr Sombat was summoned by the ruling junta but refused to turn himself in, posting a Facebook message which read: "Catch me if you can."

He previously led a pro-democracy group called Red Sunday, according to reports.

He was also one of the only prominent red shirt activists to defy the Thai military by taunting them from his Facebook and Twitter accounts.
Mr Sombat has urged followers to stage peaceful public rallies, and has encouraged the flashing of the three-finger salute from The Hunger Games films that has become a symbol of defiance against the junta.

An unnamed military official told AFP news agency that Mr Sombat would be detained at an army facility for a week.

"During that time the military will question him on his movements, behaviour and his incitement," the official said, adding that Mr Sombat would face further police interrogation and appear before a military court.

Hundreds were detained after the coup, but most have since been freed.

Meanwhile, corruption investigators have widened their inquiry into former Prime Minister Yingluck Shinawatra, investigating her private assets.

The National Anti-Corruption Commission's investigation is connected to a rice-subsidy scheme in which the government bought rice from farmers at above-market prices to boost rural incomes.

The commission had already indicted Ms Yingluck over charges of dereliction of duty, saying that she failed to heed advice that the scheme was potentially wasteful and prone to corruption.

The body has made several rulings against Ms Yingluck and her government, which her supporters suspect was part of a conspiracy to oust her from office last month.