Rejecting Maithripala Sirisena government's proposed domestic investigation rather than an international probe into the human rights violations, Tamils including activists of Tamil National People's Front, held protest in eight northern and eastern districts.
The demonstrators raised slogans holding placards and banners that read 'No local inquiry' in Tamil and English.
Sri Lanka has been subject to three UNHRC resolutions in 2012, 2013 and 2014 over alleged rights abuses by government troops during the last phase of the three decade-long war with the LTTE in 2009.
The new government persuaded the UN rights body to delay the presentation of Sri Lanka investigation report by six months.
The new government's call for a domestic mechanism rather than an international probe has not found favour with the Tamils.
They claim to have no faith in the domestic investigation based on past experiences going slow on them and producing nothing meaningful.