Khan, SP's Lok Sabha candidate from Rampur seat, was addressing an election rally here in the support of his party colleague ST Hasan, whom the SP-BSP-RLD alliance has fielded from Moradabad.
The SP leader said those who will vote for the Congress in Moradabad are like traitors.
"I have come to you carrying pain in my heart and not to deliver a speech. I have come here to warn you about the traitors, whom you have to spot as they are hiding amongst you," Khan said told the gathering.
Without taking his name, Khan also referred to Pratapgarhi as "traitor" many times during his speech.
Khan returned to electioneering after serving a 72-hour ban slapped on him by the Election Commission for his alleged "khaki underwear" jibe at Jaya Prada, who is contesting against him in Rampur on the BJP ticket.
Khan was barred from holding public meetings, processions, rallies, road shows and interviews, and making public utterances in the media for three days.
On Tuesday, the poll panel issued another cause notice for allegedly making inflammatory remarks at various places in Uttar Pradesh in the past few days.
Giving instances of his remarks, the EC said on one occasion, he had allegedly said that "fascists are trying to kill him". On another occasion, he had allegedly claimed that the prime minister has killed Muslims.
He had also allegedly said that criminals were occupying constitutional posts, in an apparent jibe at Rajasthan Governor Kalyan Singh. The EC pointed out that FlRs have been registered under various sections of the Indian Penal Code and the Representation of the People Act against him in the cases.
The notice also pointed out that the Supreme Court has noted that religion and caste cannot be used by anyone while making any statement during electioneering.