Embarrassingly for Congress, the incident occurred outside the venue where AICC observer and former Haryana chief minister Bhupinder Singh Hooda was in huddle with the party leaders to resolve differences among various factions ahead of civic polls, slated later this month.
The clash occurred after workers belonging to a faction shoved those belonging to rival group.
Kamat, a former president of Mumbai Congress, had repeatedly expressed his grouse against the "working style" of Nirupam, a former Shiv Sena leader, over distribution of party tickets for the BMC polls.
Nirupam had denied the charges.
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A senior party leader told PTI that unrest has been growing among Congress leaders and workers against Nirupam.
"Leaders like Narayan Rane, Mohammed Arif Naseem Khan, Kripashankar Singh, Gurudas Kamat are miffed with Nirupam over the way he is conducting the affairs of the party," he said.
On today's meeting, he said, "Hooda individually met all leaders who apprised him of the situation and how Nirupam's conduct was affecting the party at a time when it is making a serious bid to dislodge the Sena and BJP from the civic body."
"(Congress vice-president) Rahul Gandhi had clearly told the party leaders that names of candidates decided unanimously by the district units and district leaders would be cleared and there will be no interference from the Mumbai Regional Congress Committee (MRCC).
"However, Nirupam is overruling the names recommended by leaders," he claimed.
The leader, who was a minister in erstwhile Congress-led UPA government, said even state unit party president Ashok Chavan called upon Hooda and told him that Nirupam was not taking him into confidence for drawing party's poll strategy.