John Ashe speaks at the 68th United Nations General Assembly on Sept. 24, 2013, in New York City. Andrew Burton/Getty Images

A former finance director at a New York foundation accused of participating in a scheme to bribe a former United Nations General Assembly president on Thursday became the first defendant to plead guilty in the case.

The guilty plea by Heidi Hong Piao to five counts, including bribery and money laundering, is a major break for U.S. prosecutors examining an alleged conspiracy to bribe John Ashe, the former General Assembly president.

Piao, 52, who was also known as Heidi Park, agreed to cooperate with authorities as she admitted to having agreed with others to funnel illegal payments to Ashe, who was also the U.N. ambassador from Antigua and Barbuda.

"The monetary payments were made with the intent of influencing John Ashe, including in his official capacity," she said in Manhattan federal court.

Piao, who was finance director at the Global Sustainability Foundation, was among six people charged in the case last October.

Prosecutors allege that Ashe, the U.N. General Assembly president from 2013 to 2014, accepted $1.3 million of bribes from Chinese businessmen to support their interests within the U.N. and Antigua.

Those bribes included over $800,000 from three businessmen that were arranged through Piao and Sheri Yan, who was the Global Sustainability Foundation's chief executive, prosecutors said.

Prosecutors have also charged Ng Lap Seng, a billionaire developer from the Chinese territory of Macau who allegedly paid $500,000 in bribes to Ashe through intermediaries.

Those intermediaries included Francis Lorenzo, a now-suspended deputy U.N. ambassador from the Dominican Republic, and Jeff Yin, Ng's assistant, prosecutors said.

Ashe, Lorenzo, Ng, Yin and Yan have pleaded not guilty.

In court, Piao, who pleaded guilty to charges including bribery and money laundering, said Ashe received payments to attend a conference in his official U.N. capacity.

That admission mirrored a claim by prosecutors that Ashe received $200,000 to attend a conference hosted by a Chinese real estate developer.

Piao also said payments included money intended to pay officials in Antigua to, among other things, enter into a contract with a foreign company.

Ashe, 61, has only been charged with tax fraud, as prosecutors have said diplomatic immunity may preclude any bribery charges. But prosecutors have said they were examining the issue and likely would bring further charges.

Ashe's lawyer did not immediately respond to requests for comment.

(Reporting by Nate Raymond in New York; Editing by Lisa Shumaker and Alan Crosby)