The activists, who were protesting against Parkash for allegedly patronising a BJP drug racketeer, were stopped at Hargobindnar road and National highway 1, SP Ajinder Singh said.
Those who were detained included Punjab Youth Congress President Amarpreet Singh Lally, PPCC General Secretary and former Punjab minister Joginder Singh Mann, party state Secretary Jagjit Bittu, its Phagwara Block (urban and rural) Presidents Sanjeev Bugga and Daljit Raju, among others, he said.
"Now when their own leaders have started exposing the state government, they got unnerved as they know that Congress will take them to task after forming government in 2017," Lally said.
The Congress leaders alleged that Amritsar district Akali Dal President, Upkar Singh Sandhu and Kapurthala district BJP General Secretary, Gurdeep Singh Deepa, had openly accused state minister Bikram Majithia and local MLA Som Parkash of patronising drug mafia in SAD and BJP.
The detained leaders were released later, police said.