Lebanon’s government resigned amid accusations of entrenched corruption and negligence after the August 4 explosion that killed nearly 200 people and devastated entire districts of Beirut.
Citing growing poverty, unemployment and inflation, Jean-Yves Le Drian told RTL radio: “This country is on the brink.
“The risk today is the disappearance of Lebanon.”
He said Lebanon needs to urgently form a government and institute reforms in order to save itself.
French President Emmanuel Macron will be in Lebanon, a former French protectorate, next week on a three-day visit.
He will offer French support after the devastating port explosion, but will ensure that millions in international aid is going to those who need it.
Mr Le Drian added: “We will not sign a blank cheque for a government that does not implement reforms,” notably of public services and the banking system.
Canadian foreign affairs minister Francois-Philippe Champagne, who is currently in Beirut, also said reforms are badly needed in the country.
Nineteen people, most of them port and customs officials, have so far been arrested in connection with the blast, and Mr Champagne said Canada is ready to assist with the investigation.
Mr Champagne told reporters that he discussed with the outgoing Lebanese defence minister an “understanding on the conditions that the Royal Canadian Mounted Police will participate in the investigation”. Two Canadian citizens were killed in the explosion.
He added that Canada is more than happy to work under conditions that “our assistance will give faith to the Lebanese people that this is an investigation that will go to the bottom of things”.
He added: “This blast is the tragedy of all tragedies. It embodies all the tragedies that we have seen in decades in Lebanon.
“Impunity needs to cease, reforms need to take place and I would say leaders need to listen.”