DSP Zia-ul-Haq was killed by a mob in Pratapgarh on Saturday when he had rushed there after a village head was shot dead over a land dispute. The slain officer's wife had accused Raja Bhaiya for the attack.
"The SP government was trying to shield the former minister. Otherwise he (Raja Bhaiya) would have been arrested by now. Till date he has not been arrested," Mayawati told reporters in New Delhi.
She said the protests by Muslim students at the Aligarh University and Allahabad University were valid as an FIR has been filed against the former minister but he has not been arrested yet.
On her demand for imposition of President's Rule in UP, Mayawati said it was upto the Centre to take a decision.
Meanwhile, SP member Naresh Agarwal said the party had no objection to the conduct of a second postmortem of the slain DSP.
"The post-mortem was conducted in the presence of TV cameras. We have no objection to conducting post-mortem again," he said when asked about the demand of the police officers wife for a second autopsy in the case.
Agarwal said UP Chief Minister Akhilesh Yadav has already recommended a CBI probe into the incident.