Thirty-one Dalit activists have been arrested in Lucknow.
The activists included retired IPS officer and activits SR Darapuri.
Police said the activists were trying to take out a rally, which they did not have permission to do.
News reports said the activists had held a press conference at the Lucknow Press Club at which they had talked about atrocities against Dalits and also the 50 Dalits who had been offloaded from a train at Jhansi on Sunday.
The rally had been planned after the press conference.
The 50Dalits had been travelling to Lucknow with a 125-kg bar of soap which they were going to give to Uttar Pradesh chief minister Yogi Adityanath.
Earlier this year, members of a scheduled caste in a UP village had alleged that they had been given bars of soap and been asked to "clean up" for a visit by the chief minister.
All 31 activists were later released.