Usubov's comments came as the Azadliq (Freedom) opposition coalition said it would defy a ban from Baku city authorities and hold a protest march in the center of the Azerbaijani capital on 25 September.
Tension is running high in Azerbaijan as the country nears election day. The opposition claims the government is seeking to falsify the polls.
Authorities in turn accuse the opposition of attempting to destabilize the situation. Usubov today also warned former parliament speaker Rasul Quliyev that he will be arrested as soon as he enters Azerbaijan. Quliyev, who has been living in exile since 1996, is running as an opposition candidate in the upcoming polls. He is wanted in Azerbaijan for allegedly embezzling $100 million -- a charge he denies.
For RFE/RL's full coverage of events in Azerbaijan and the runup to the November elections, see "News And Features On Azerbaijan"