“They vandalised a police van in a militant style,” he said at a discussion on Wednesday referring to the incident outside the High Court the previous day.
The BNP, however, claimed the attackers were infiltrators, not its activists.
Quader said the BNP was hatching another conspiracy ahead of the national election.
“They have attacked police just like the militants do. This is beyond any democratic practice, but they claim to establish democracy.”
“It only reflects the party’s political bankruptcy.”
The court’s verdict will be based on evidence, he said. “Will the foreigners influence the court?”
A Dhaka court is expected to hand down its verdict in the Zia Orphanage Trust graft case against Khaleda on Feb 8.
Advising ruling party activists, Quader said: “We will not instigate them, but will not spare them if attacked. Be prepared.”