LONDON — Britain’s problem-plagued inquiry into child sex abuse finally began Monday, years after it was organized, amid revelations that entertainers, clergy and senior politicians were involved.

The far-reaching probe began hearing evidence after being beset by criticism and delays. It will scrutinize 13 institutions for child protection failings, including the army and local authorities.

The committee, chaired by Professor Alexis Jay, began its work by hearing evidence about a migration program that oversaw the resettlement of an estimated 100,000 vulnerable British children in Canada, Australia, New Zealand, and Zimbabwe from the 1930s to the 1970s.

The program, funded by British taxpayers, was said to have been justified by the government as a way of cutting care costs for children, and an opportunity to meet labor shortages in British colonies.

Aswini Weereratne of the Child Migrants Trust described the mass migration as ‘‘forced or coerced deportation.’’ She said some of the children sent abroad by the British government suffered ‘‘torture, rape and slavery.’’

Associated Press