United Nations chief Ban Ki-moon ordered an audit Thursday to shed light on UN ties to a Chinese real estate mogul and foundations allegedly set up to funnel bribes to UN diplomats.

Former General Assembly president John Ashe was arrested on Tuesday for allegedly taking $1.3 million in bribes from billionaire developer Ng Lap Seng to promote his plan to build a UN conference center in Macau.

Ashe, a former UN ambassador from Antigua and Barbuda, also is accused of helping Chinese businessmen buy hotels in his Caribbean home country, according to a criminal complaint filed in a New York court.

Declaring there can be "no tolerance for corruption at the United Nations," Ban asked the UN internal oversight office to carry out the audit, two days after the bribery charges were made public.

The review will look at "the interaction between the United Nations and the Global Sustainability Foundation and the Sun Kian Ip Group" set up by Ng, Ban's spokesman Stephane Dujarric said.

The audit will examine "the use of any funds received from these entities," he added.

The United Nations has reviewed a $1.5 million donation from the Sun Kian Ip Group to the UN Office for South-South Cooperation, established by the UN Development Program.

Dujarric said the funds were used to organize recent conferences in Bangladesh and in Macau, as well as two other meetings scheduled for next year.

But the spokesman insisted that funds were spent "in full compliance with UN standards and guidelines."

"There is no evidence that the funds received were misdirected or misappropriated," he said.

None of the office's staff is under investigation.

- Slow to respond -

The United Nations faced questions over its failure to take swift action to address the wide-ranging bribery scam involving the ex-president of the assembly.

The embarrassing revelations follow the Iraqi oil-for-food scandal in which an independent commission found widespread abuse in the UN program to sell Iraqi oil in exchange for humanitarian aid.

The UN spokesman described the decision to launch an audit as "an important step" even though the review is limited to the two entities.

Also arrested on Tuesday was Francis Lorenzo, a UN deputy ambassador from the Dominican Republic, who heads South-South News, a UN-accredited media outfit that reports on development issues.

Lorenzo's lawyer, Brian Bieber, told AFP that his client "acted in good faith at all times" but may have been misled by Ashe and the Chinese developer's associates.

"We welcome any and all audits," said Bieber.

Ashe's wife, environmental campaigner Anilla Cherian, who was not charged in the bribery scheme, was allegedly paid $2,500 per month from January 2001 to December 2014 to work as a consultant for South-South News.

The media outfit received $12 million from Ng, according to the complaint, and paid for a family vacation for Ashe at a swanky New Orleans hotel that charged $850 per night.

Ashe allegedly was paid $20,000 per month to serve as the honorary chairman of the Global Sustainability Foundation, according to the criminal complaint.

The foundation's chief executive Sheri Yan and financial director Heidi Hong Piao were among the six charged in connection with the bribery scheme.

The foundation's website names Edith Kutesa, wife of another former General Assembly president, Sam Kutesa of Uganda, as a member of its board of directors. Kutesa has not been cited for any wrongdoing.