Amnesty International on Tuesday called for the immediate and unconditional release of Maurice Kamto, leader of the opposition party Cameroon Renaissance Movement (MRC), after he was arrested in the country's economic capital Douala.

Kamto who came second in 2018 October's presidential election which he claims was rigged, was detained on Monday at the home of another politician, prompting some 300 people to protest outside.

Party treasurer Alain Fogue was also arrested on Monday, and over the weekend Paul-Eric Kingue who ran Kamto's election campaign and rapper Valsero, were also detained alongside 115 other people, who attended opposition protest marches in several towns.

Amnesty International warned that the arrest of Kamto and his staff, signals an escalating crackdown on opposition leaders, human rights defenders and activists in Cameroon.

Amnesty's West and Central Africa director Samira Daoud, said he authorities must immediately and unconditionally release them, as well as peaceful protesters detained at the weekend simply for exercising their rights to freedom of expression and peaceful assembly.