"Parasitic" multi-nationals have no more moral right to avoid tax than people did to own slaves or employ child labour before those practices were abolished, bosses have been warned by a leading international development charity.

A report issued by Christian Aid backed the verdict of Margaret Hodge, chairwoman of Westminister's Public Accounts Committee, that it was "evil" to dodge paying everything the Treasury expected - even if it was strictly within the law.

Revelations about the extent to which giant firms such as Google, Amazon and Starbucks and wealthy individual celebrities have exploited loopholes to minimise bills have sparked condemnation - with Prime Minister David Cameron calling it "morally wrong".

The aid charity's chairman, former archbishop of Canterbury Rowan Williams, said the practice "simply feels wrong to most people" and the concept of justice had to include a "positively renewed set of social interactions and mutual nurture".

Stamping out corporate avoidance was crucial to cutting the need for foreign aid - with the world's poorest countries losing more in tax each year than they received in international financial support, he noted.

The introduction to the report said: "An action may be technically legal but that does not make it moral.