(CNN) UNICEF Deputy Director Justin Forsyth has resigned after allegations he behaved inappropriately toward female staff members during his time as chief executive at Save the Children.

Forsyth said Thursday he was not resigning from the United Nations children's agency because of "mistakes" he made at Save the Children, but because of the "danger of damaging" the aid organizations and their cause.

His departure comes two days after Save the Children confirmed that concerns were raised about Forsyth's conduct in 2011 and 2015 , while he led the charity.

In a statement Tuesday, the international charity said Forsyth was twice subject to investigation after complaints from three women.

On both occasions, the investigation led to "unreserved" apology from the chief executive and "the matters were closed," the statement said.

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