The president of the Anti-Corruption Unit announced yesterday that two more government officials have been summonsed for questioning over their involvement in a blackmailing and extortion case.

Sam Sarith, a 43-year-old personal assistant to a secretary of state at the Ministry of Justice and a lieutenant colonel in the military, was arrested on Monday for threatening and demanding money from a businessman, according to Om Yentieng, ACU president.

"He is still detained at the ACU and being questioned. He will soon be sent to the municipal court," Yentieng said during a public forum on corruption held in the capital.

The two summoned officers also worked in the Ministry of Justice, where a pending lawsuit against businessman Hun Buntheoun involving a 2008 property sale was used as blackmail material to extort more than $1,000 from him, according to a penal officer at the Ministry of Interior.

Yentieng declined to name the two officials yesterday, adding only that they are due for questioning on September 15.

Buntheoun, allegedly president of a real estate firm called Sambo Ratanak Company based in Phnom Penh, could not be reached for comment.