Hassan Sylla Bakary, the communications minister, said on Wednesday that a group of individuals “with bad intentions sought to carry out an action to destabilize the institutions of the republic”.
“They did not count on the valiant security forces who have tracked them since December 2012 and who, this morning, neutralized them,” Bakary said.
He said the suspected plotters had been handed over to the state prosecutor. He did not reveal their identities or give further details of the plot.
Reuters reported that at least one member of parliament, an opposition figure named Saleh Maki, was also detained.
The former French colony has a long history of coups and rebellions, and Deby himself led rebel troops into the capital, N’Djamena, in 1990 to seize power.
Deby has since won four elections and cast himself as an ally of the West against al-Qaida-linked fighters across the vast, Sahel region.
Deby deployed about 2,000 troops to Mali earlier this year to help drive out fighters who had seized the northern two-thirds of the country, earning him the gratitude of the French spearheading the operation there.
However, the president has plenty of enemies both at home and abroad.
The UFR, a Chadian rebel coalition that laid down its weapons in 2010, said in March that they would relaunch their rebellion after Deby failed to enter talks with them.
Last week, Deby accused neighboring Libya of allowing Chadian mercenaries to set up a training camp from where they could seek to destabilize his country, a charge Libyan authorities rejected.