The red shirts plan to make a merit-making ceremony at Wat Plabplachai to mark the fifth anniversary of the crackdown on protesters near the Democracy monument in 2010.
Winthai said the planned gathering of the red shirt leaders may violate NCPO order number 3/2558 and Article 44 of the interim charter.
Red shirt leader Nattawut Saikua said his group’s objective in meeting the Department of Special Investigation on Tuesday was to ensure that the probe into the crackdown would continue in a transparent and fair manner.
The red shirts sought the meeting following reports that a new investigative team had been appointed to oversee the case, he said.
He denied that red shirts were trying to exert political influence and meddle in DSI affairs.
“We want to know the progress of the case and what is the timeframe of the case under the new investigative team,’’ he said.