The chief executive of Oxfam who vowed to clean up the charity after the Haiti sex scandal has been forced to deny covering up similar wrongdoing at his former workplace.

Danny Sriskandarajah, who joined Oxfam as chief executive last year after the former chief and his deputy quit in the wake of the revelations, promised ‘systematic and cultural changes’ at the charity.

Yet a previous employee at the Royal Commonwealth Society (RCS), said that while under Dr Sriskandarajah’s leadership in 2009 a senior figure was allowed to ‘quietly resign’ after it emerged he had paid for sex during taxpayer-funded trips to Amsterdan and Los Angeles.

Nigel McCollum, the former head of public affairs at the RCS, told the Mail on Sunday that he blew the whistle on the employee but was shocked to find little action was taken, and the man was allowed to move to another job in the charity sector.

Mr McCollum said he himself ended up being ostracised, made to sign a gagging order and eventually forced out of the charity.

Speaking about the Haiti cover-up, Mr McCollum said: “This is remarkably similar to what happened on his watch at the RCS.

“This man covered up a scandal there, so he should not have been hired to clean up Oxfam. It's staggering.”