Reacting to the scandal engulfing the British charity, Jovenel Moise said the actions were an “extremely serious violation of human dignity”.
His attack comes as reports suggest Haiti is preparing to launch a criminal investigation into claims senior aid workers paid for sex after the devastating 2010 disaster.
Mr Moise tweeted: “There is nothing more outrageous and dishonest than a sexual predator who uses his position as part of the humanitarian response to a natural disaster to exploit needy people in their moment of greatest vulnerability.
“What happened with Oxfam in Haiti is an extremely serious violation of human dignity.”
Oxfam was delivering humanitarian help after the 7.0-magnitude quake left more than 200,000 people dead.
It is claimed the Oxford-based charity concealed the findings of a 2011 inquiry into claims senior staff, including Haiti’s national director, paid prostitutes for sex. Four staff were sacked and three resigned before the end of the investigation.
Bocchit Hammond, Haiti’s ambassador to the UK, said former Oxfam chief executive Dame Barbara Stocking had insulted his country by suggesting Haitian authorities would not have dealt with the allegations.
He said: “Even though there was a chaotic situation after the earthquake… the state of Haiti did not cease to exist.
“How can you not report those crimes because you believe nothing would be done? It is a cover-up… Because the top executives here in London were informed.”
Yesterday it emerged the six-bedroom complex in the Haitian capital Port au Prince hosting “Caligula-style orgies” was so notorious it was known as the “whorehouse”.
The Express understands that at no stage has International Development Secretary Penny Mordaunt requested current Oxfam chief executive Mark Goldring resigns.
One senior government source said: “Where is the moral leadership from Dfid? Questions should be asked.”
Oxfam, which issued an “unreserved apology” over its handling of the allegations, which led to the resignation of its deputy chief executive Penny Lawrence, received £31.7million of British taxpayers’ cash from 2016 to 2017.
Ms Mordaunt said: “I know people will be worried… but we need to be guided by what the Charity Commission are doing and also I have made it very clear to Oxfam what we expect to see from them.”
Last night the scandal deepened when Oxfam International chairman Juan Alberto Fuentes was arrested with ex-Guatemalan leader Alvaro Colom, in a corruption probe.
A petition seeking the end of a commitment to spend at least 0.7 per cent of national income on foreign aid has now gained nearly 50,000 signatures.
The Daily Express has backed reader Robert Barnes’s call to scrap the target, which saw £13.4bn leave the UK last year.
His petition needs 100,000 signatures by March 14 to force a debate in Parliament.
To sign the petition visit https://petition.parliament.uk/petitions/200292