Abhisit Vejjajiva, Thailand's caretaker prime minister, has told Al Jazeera that investigations into last year's political violence have been too slow.
The clashes between security forces and anti-government protesters in Bangkok in 2010 left several people dead and hundreds injured.
Vejjajiva has been negotiating with the main opposition party about working together ahead of next month's general election amid fears of more unrest.
Abhisit is in the midst of a tough electoral battle against Thaksin Shinawatra's allies in the Puea Thai party, who want an amnesty for politicians who have been charged or convicted if they win the July 3 vote.
The opposition is accused of inflaming political tensions by "whitewashing" the crimes of their de facto leader, Shinawatra.
Al Jazeera's Wayne Hay reports from Bangkok.