He said the charity had made "serious errors" when choosing to remove the alleged offenders from their posts discreetly, and without notification to the Haitian authorities.
The British arm of the world-famous organisation is set to be investigated by Haitian authorities, with the sex scandal raising questions over the future of the charity's funding.
The operating ban on Oxfam GB comes just a fortnight after details of an internal investigation into alleged sexual misconduct by seven members of staff were exposed.
The organisation has since apologised for downplaying the claims of misconduct.
Oxfam will continue working on construction and development projects in Haiti, helping people through other affiliate members, but anticipates that Oxfam GB's temporary suspension will have a significant impact on its work.
Mr Fleurant added that the allegations surrounding the Oxfam sex scandal are a "serious violation of the dignity of the Haitian people".
According to reports by Reuters, Haiti's planning and external cooperation minister Aviol Fleurant said: "If during the two month-long investigation I find out there is a link between the aid funds that Oxfam received on behalf of Haiti and the crime that has been committed, we will. declare Oxfam Great Britain persona non grata and they would have to leave the country without further delay".
Four people were dismissed for "gross misconduct" and two others resigned after being accused of using prostitutes.
A young Haitian woman told The Times newspaper she had had relations with the former Oxfam country director in Haiti, Roland Van Hauwermeiren, when she was 16 and he was 61.
The suspension of the charity's right to operate did not apply to Oxfam Canada, he said.
The UK Government is also deciding whether to end Oxfam's multi-million pound yearly funding, while the charity has said it will not bid for any new Government contracts at present.
The Haiti scandal has opened the charity to greater scrutiny, leading to 26 new cases of sexual misconduct, most involving its worldwide operations.
Oxfam's troubles have also been followed by other allegations about misconduct in the charity and global aid sector.