The Church in Goa and the opposition Congress on Sunday came down heavily on what they described as "excessive strength" allegedly used by police to crack down on a peaceful protest that sought a thorough probe into the death of Catholic priest-activist Bismarque Dias.

In a statement in Panaji, the Council for Social Justice and Peace, the social wing of the influential Catholic Church in Goa, termed the police action as "unjustifiable."

The police on Saturday arrested nearly 300 people for protesting in the state capital in violation of section 144 of the Criminal Procedure Code.

"The forceful detention of bystanders or commuters from the ferry boat assuming them to be protesters without any provocation is abuse of power. Moreover, arresting those who were peacefully dispersing from the scene is also unjustifiable," CSJP executive secretary Savio Fernandes said.

Saturday's protesters included civil society activists, representatives of political parties as well as friends and family of Dias, whose body was fished out of the Mandovi river on 7 November.

The mysterious death of Dias -- who was leading a string of agitations against controversial real estate projects across Goa -- and the police flip flops on the nature of his death had led to a series of protests and candlelight vigils across the state.

"The Council calls on police to respect the constitutional rights of the people to assemble and protest peacefully and also to exercise judicious discernment in action while maintaining law and order," Fernandes said.

Earlier, at a press conference organised in the capital city of Goa, the Congress demanded a judicial inquiry into the police action against senior citizens at Saturday's protest.

"We demand a judicial inquiry into the condemnable attack on elderly men and women at the protest. What happened is not right," Congress spokesperson Agnelo Fernandes said.