Chad's national assembly has authorised President Idriss Déby's government to extend by 15 days a state of emergency.
The state of emergency was declared following a rebel attack on the capital N'Djamena earlier this month.
Mr Déby had assumed the additional powers on February 14th to tighten security across the central African country after the rebel assault, in which at least 400 civilians were killed.
Under the country's constitution, Mr Déby had to seek parliament's authorisation to prolong the state of emergency, which gives the government broad search-and-arrest powers and permits control of media reporting.
International and Chadian human rights groups have accused government security forces of arbitrarily arresting opponents of Mr Déby.
Following a request from French President Nicolas Sarkozy during a brief visit to Chad on Wednesday, Mr Déby announced an international commission to investigate the fate of two missing opposition leaders.
Their families say they were dragged from their homes by government troops on February 3rd.