Barnardo's is being sued for £400 million over claims that it sent vulnerable children to work as farm labourers in Canada between 1870 and 1939.
The charity said it is taking the claims "extremely seriously".
A lawsuit in Canada, initiated in Ontario superior court, is claiming the £400 million in compensation on the grounds that the charity sent children to the country before the war, many of which had living parents who were not informed.
The lawsuit claims that many of the children and young people were subsequently abused.
A web site has been set up by lawyers to one of the "Barnardo's boys", Harold Vennell, encouraging others to join the class action. A lawyer said the charity shipped 30,000 children to Canada and that around 5,000 are still alive.
A spokeswoman for Barnardo's said: "We take any complaint of this nature seriously, but as our legal representatives are now handling the matter, we feel unable to comment further.