"This attack is most unfortunate. Such acts are against the basic tenets of democracy. But who is behind this? Who all are angry with Kejriwal? All these things should be fully investigated. Ever since he has been raising his voice against corruption, some people have been antagonised," BJP spokesperson Shahnawaz Hussain told PTI.
He said the antecdents of the attacker who had thrown a slipper at Kejriwal in a public programme in Lucknow should also be probed thoroughly.
BJP insisted there has been a concerted attempt to tarnish the image of Team Anna.
The opposition also hit out at the BSP-led Mayawati government in Uttar Pradesh for "failing" to give adequate protection to Kejriwal, knowing that he is under threat.