The Centre of the Resolution of the Emergency Situation (CRES) will have to defend itself against allegations that some red shirts were being detained at a military base in Kanchanaburi.
"We will ask for information from their detainees' relatives too," the subcommittee's chairman and NHRC commission Dr Niran Pitakwatchara said.
Pheu Thai Party spokesman Prompong Nopparit brought the case to NHRC's attention.
Allegations emerged on Monday, when military chiefs insisted that no red shirts were being detained in Kanchanaburi because there were no detention facilities there.
"We will gather information from those involved before conducting field trips to find the truth," Niran said.
He added that his panel would also invite representatives from relevant agencies such as CRES, the Department of Special Investigation and National Police Office to discuss the subcommittee's findings that many red shirts at the Bangkok Remand Prison were being subjected to human-rights violations.
"Even though Bangkok is under the state of emergency, the government has to respect the human rights of the detainees," Niran said.