A national protest would be justified if the government failed to conduct a socio-economic impact assessment before increasing energy and water tariffs, according to Alternattiva Demokratika.

Citing press reports, AD energy spokesman Ralph Cassar said it was "regressive and socially unacceptable" that low energy users would face a proportionately higher increase in their energy bills than high energy users.

Last week, opposition leader Joseph Muscat called on the country to unite in a national, non-political protest against the new water and electricity tariffs.

AD sustainable development spokesman Carmel Cacopardo criticised ministers Austin Gatt and Tonio Fenech for tackling the water and electricity problem in a "mechanical way" and said they had approached the issue in the same way the Labour government had done in 1997.

"A responsible government would have quantified the economic and social impact of its policies in this sector - something which it seems was not even considered. The greater burden should be carried by those who waste energy and water," Mr Cacopardo said.