Chad is shutting down the Qatar embassy in N'Djamena and on Wednesday asked diplomats to leave within 10 days.
The central African nation has accused the Gulf Arab state of trying to destabilise the country via its northern neighbour Libya.
"In order to safeguard peace and security in the region, Chad calls on Qatar to cease all actions that could undermine its security as well as those of the countries of the Lake Chad basin and the Sahel," the foreign ministry said.
It is not the first African state to move against Qatar following its rift with other Gulf states.
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Chad, Mauritania and Senegal all recalled their ambassadors from Qatar in June.
They acted after Saudi Arabia, the United Arab Emirates, Bahrain, Yemen and Egypt broke off diplomatic and trade ties with Qatar, accusing it of supporting Islamist extremists, a charge Doha denies.
Senegal said this week that it had reinstated its ambassador to Qatar after having recalled him three months ago, in a bid to encourage a peaceful resolution to the feud.
