A former president of the UN General Assembly, John Ashe, was arrested on Tuesday and charged with taking $1.3 million in bribes from Chinese businessmen in a corruption scandal that stunned the world body.

UN Secretary-General Ban Ki-moon said he was "shocked and deeply troubled" by the charges, which were unprecedented in the UN's 70-year history.

Ashe, who served as assembly president for a year from September 2013, allegedly took bribes in exchange for backing a proposed UN conference center in Macau promoted by wealthy Chinese developer Ng Lap Seng.

"Among other things, Ashe accepted over $500,000" from Ng who was "seeking to build a multi-billion dollar, UN-sponsored conference center in Macau," the complaint said.

New York police arrested the 61-year-old former UN ambassador for Antigua and Barbuda at his home in Dobbs Ferry outside New York and three others were detained in New York early Tuesday.

US Attorney Preet Bharara said Ashe was using the United Nations as a "platform for profit", pushing for the Macau project and advancing Chinese interests in his Caribbean home country.

In exchange for payments, Ashe submitted a written request to Ban "which claimed that there was a purported need to build the UN Macau Conference Center," the complaint said.

Ng and others used the March 2012 letter from Ashe to promote the conference center which was to house a "Global Business Incubator" to foster South-South cooperation in the private sector.

Ashe, who holds Antiguan citizenship and is a US resident, served as ambassador when he wrote the letter, a position he held until November 2014.

Francis Lorenzo, a UN deputy ambassador from the Dominican Republic, was also jailed along with Shiwei Yan and Heidi Hong Piao on multiple bribery-related counts.

Last month, Ng was arrested in New York along with associate Jeff Yin for smuggling more than $4.5 million in cash into the United States over a two-year period.

The six are accused of using a fake non-government organization to carry out the bribery scheme. Lorenzo, the NGO's honorary president, was paid a $20,000 salary.

- Rolex watches, tailored suits -

"If proven, today's charges will confirm that the cancer of corruption that plagues too many local and state governments infects the United Nations as well," Bharara told a news conference.

The former UN assembly chief "sold himself and the global institution he led" for Rolexes, suits and a private basketball court all paid for by the wealthy Chinese developer, said the attorney.

The bribes allegedly were paid from 2011 to December 2014.

Details of Ashe's luxurious lifestyle listed in court documents showed that he purchased two Rolex watches worth $54,000, took out a $40,000-lease for a new BMW and ordered expensive tailored suits from Hong Kong worth $59,000.

Ashe received $800,000 from Chinese businessmen to advance their interests at the United Nations and with the Antigua government, the documents said. Antigua's prime minister allegedly received a cut of the bribe money.

The bribe payments also went to pay for family vacations and the construction of a basketball court at Ashe's house.

UN spokesman Stephane Dujarric said UN officials first learned of the charges when media reports surfaced on Tuesday and had not been contacted by the US authorities to help in the investigation.

"The secretary-general was shocked and deeply troubled to learn this morning of the allegations against John Ashe, which go to the heart of the integrity of the United Nations," he said.

The current president of the General Assembly, Mogens Lykketoft of Denmark, said he was "deeply shocked" and declared that "the United Nations and its representatives should be held to the highest standards of transparency and ethics."

But he declined to say whether any new measures would be introduced to oversee the conduct of ambassadors and UN leaders in light of the corruption scandal.

"I am in no position to investigate myself or to make new regulations without a specific decision from the General Assembly," said Lykketoft.