Siliguri police commissioner Anand Kumar told PTI that the two leaders were detained for their own protection as a mob of Trinamool Congress and CPI-M workers clashed outside the party office Anil Biswas Bhavan yesterday.
"Ashok Bhattacharya and Jibesh Sarkar were not arrested but only detained. They were released today morning," he said.
Bhattacharya is a CPI-M state committee member and was urban development minister in the erstwhile Left Front government and Sarkar is a member of the Darjeeling district committee.
"The police had wanted to free us yesterday itself but we had demanded to know the reason of our detention," he said.
A policeman and three journalists were among those injured in the clash between TMC supporters, who took out a procession against the attack on Chief Minister Mamata Banerjee and Finance Minister Amit Mitra by SFI in Delhi, and the CPI-M. The clash ensued when glass bottles filled with liquid were allegedly thrown at the procession from the CPI-M office.