BJP General Secretary Raghunath Malkapure issued the notice, asking Kumar to reply within seven days.
Earlier in the day, Dhananjay Kumar had slammed Chief Minister Jagadish Shettar for his 'failure' to protect the state's interests on the Cauvery issue. He had also recently criticised Deputy Chief Minister K S Eswarappa over it.
Kumar, whom Shettar had recently sacked as Special Representative of Karnataka in Delhi, said he was yet to receive the notice and would then decide whether to reply to it.
Ruling BJP leaders including Yeddyurappa have been criticising four union ministers representing Karnataka, particularly Krishna, for their "failure" to convince the Prime Minister about the water-situation.
