At least 12 leaders and workers of the Trinamool Congress (TMC), including those injured in an alleged attack by BJP workers on the previous day, were arrested in Tripura's Khowai district on Sunday for "violating Covid norms", police said.

TMC national general secretary Abhishek Banerjee, who is Bengal Chief Minister Mamata Banerjee's nephew and the de facto number 2 in the party, reached Agartala and left for Khowai to meet the arrested party workers, who will be produced before a court amid tight security arrangements.

Police said that the 12 TMC members were arrested for violating Covid restrictions by travelling after the imposition of night curfew at 7 pm.

Tripura TMC spokesperson Ashish Lal Singh said that party leaders including himself, Debangshu Bhattacharya, Tania Poddar, Sudip Raha and Jaya Dutta have been arrested.

Raha and Dutta had sustained injuries when their vehicle was allegedly attacked by BJP workers at Ambassa in Dhalai district on Saturday.

"After the attack, we were returning to Agartala through National Highway 8 when the police stopped our vehicles at Khowai and took us into custody stating that there could be more attacks on us by 'miscreants'. Indeed, BJP activists had gathered at several places on NH 8 to attack us," Singh said.

However, early in the morning, police said that the TMC members were arrested for violating Covid restrictions.

Meanwhile, three senior TMC leaders, including Abhishek Banerjee, West Bengal Education Minister Bratya Basu and Rajya Sabha MP Dola Sen, reached Agartala and left for Khowai to meet the arrested members.

Banerjee had earlier visited Tripura on August 2, when his convoy was also allegedly attacked by BJP workers.

Strongly criticising Saturday's attack, TMC leaders alleged that the incident proved that there "goonda raj" (lawlessness) in Tripura, and the BJP has sensed its defeat in the 2023 assembly elections in the state.

Denying the involvement of its activists in the attack, the BJP claimed that the TMC is a non-factor in Tripura, and Bengal's ruling party is spreading the "virus of political violence" in the northeastern state, where "outsiders" are fomenting trouble.

Shortly after the incident, BJP and TMC supporters had faced off and staged road blockades 500 m apart on NH 8, forcing Chief Minister Biplab Deb to take a detour to return to Agartala after attending some programmes in Dharmanagar.

TMC workers led by Subal Bhowmik, a former vice-president of Tripura BJP who recently switched sides, were protesting the alleged ransacking of a TMC party office by saffron party workers in Batarasi area of Dharmanagar on Friday night.

The Bengal CPI(M) has also criticised the attack, but also took a dig at the TMC alleging that it had kept mum when Left workers were earlier attacked in BJP-ruled Tripura.