Security forces arrested opposition leader Saleh Makki and several others following what the government said was a coup, the BBC reports.
"A small group of ill-intentioned individuals attempted to carry out a destabilization plot against the institutions of the republic," a government statement said.
The military said the saboteurs were "neutralized." The BBC reports the capital N'Djamena was calm and it was unclear how many people were involved or to what degree opposition leaders played a role in the alleged coup attempt.
Deby seized power in a coup in 1990. He survived attacks on the capital in 2006 and 2008 from rebel forces from eastern Chad.
Chad, divided along Muslim and Christian lines, has a long history of political instability and internal conflicts.
The U.S. government in February offered $50 million to the military in Chad to help support French operations in Mali.