A UN office says it is rejecting a $15 million offer from a foundation now under scrutiny after its leader was arrested and accused in an alleged bribery scheme.

The director of the UN Office for South-South Cooperation told The Association Press in an interview Friday that his office was "not pursuing" the offer made by the Sun Kian Ip Group Foundation earlier this year.

The foundation's leader, Macau billionaire Ng Lap Seng, is accused of lying about plans for $4.5 million in cash brought into the U.S. over several years aboard private jets. Also accused in the alleged scheme is former UN General Assembly President John Ashe, who the U.S. criminal complaint says took over $1 million in bribes from Ng and others to pave the way for lucrative investments.

The case has raised questions about the money the UN and its key players accept from outside entities and how donations and partners are vetted.

The UN official, Jorge Chediek, said his office is conducting an internal review of "all details of relationships" with the Sun Kian Ip Group Foundation and with the Global Sustainability Foundation, whose leader, Sheri Yan, is also accused in the alleged scheme. Yan was an adviser to Ashe during his presidency from September 2013 to September 2014.

The internal review is in addition to an audit that UN Secretary-General Ban Ki-moon ordered Thursday into the two foundations and their contacts with the UN

The UN Office for South-South Cooperation promotes co-operation between developing countries, including China. Chediek, who became director after Zhou Yiping retired last month, said his office has not been contacted by U.S. authorities about the case.

In a statement earlier this week, the office said it had received $1.5 million from the Sun Kian Ip Group Foundation and had used it, along with funding from a variety of sources, to organize conferences in Bangladesh in May and in Macau in August.

On Friday, Chediek said the foundation's $15 million offer was "never operational" beyond the $1.5 million his office used. He said all of the $1.5 million had been accounted for, with no evidence of misuse. His office conducted due diligence on the foundation, even travelling to Macau in April, he said.

He said there was no "institutional relationship" between his office and the Global Sustainability Foundation, but the review continues.

Ashe is also listed as chairman of an organization called the South-South Steering Committee for Sustainable Development. Another organization called the International Organization for South-South Cooperation lists as president Francis Lorenzo, a deputy UN ambassador from the Dominican Republic who also has been charged in the alleged bribery scheme.

Both organizations feature logos similar to the UN one. Neither has been announced as a target for any UN investigation. Chediek, acknowledging the confusion, stressed that the term "South-South" has not been copyrighted.

But he suggested "maybe raising the independent profile" of his office in the future.