The Election Commission on Saturday issued notice to senior Congress leader Digvijay Singh for allegedly threatening to "use" the Central Bureau of Investigation (CBI) against Uttar Pradesh Chief Minister Mayawati.
Terming it as violation of the model code of conduct, the panel asked him to reply by 5 pm on Sunday why action should not be taken against him, the Commission said in a statement in New Delhi.
At a campaign rally on Monday at Mallwan in Hardoi district, about 110 km from Uttar Pradesh capital Lucknow, Digvijay Singh reportedly said the central government would "use" the CBI against Bahujan Samaj party (BSP) chief Mayawati if she continued to harass Congress workers.
The Commission said: "The party in power, whether at the centre or in the state or states concerned, shall ensure that no cause is given for any complaint that it has used its official position for the purposes of its election campaign."
The poll panel said it had seen the video recording of his speech.
On Wednesday, the Uttar Pradesh police booked Digvijay Singh for violating the model code of conduct.