The Global Witness report alleges that a Cyprus company belonging to the president’s daughter, Claudia Sassou-Nguesso, bankrolled the purchase of the Trump apartment in July 2014. (The Portuguese newspaper Expresso has previously reported on aspects of the purchase and its connection to the daughter of the president of the Republic of Congo.)

A spokesman for President Sassou-Nguesso and a representative at the Republic of Congo’s embassy in Washington did not respond to requests for comment.

Global Witness — which is funded in part by the billionaire George Soros’s foundation — followed a money trail that began with a Brazilian company receiving a series of lucrative public contracts from the Republic of Congo’s government. Money from one of those contracts wound up in the bank account of a company in Cyprus, according to the report. Ownership of the company was transferred to Ms. Sassou-Nguesso in July 2013.

In January 2014, the Cyprus company received nearly $20 million, apparently in Republic of Congo taxpayer funds, through a contract with the country’s government, according to a Portuguese police report reviewed by Global Witness. Six months later, the Cyprus company paid for Unit 32G in the Trump building on Columbus Circle.

A 2006 real estate listing for the corner apartment shows floor-to-ceiling windows with northern and western views, a bathroom with pink marble walls and golden fixtures and “capacious closets.” The building is outfitted with a spa, swimming pool and 24-hour food service.

Image Claudia Sassou-Nguesso, the daughter of the president of the Republic of Congo, in 2012. Credit... Guy Gervais Kitina/Agence France-Presse — Getty Images

Letters cited by Global Witness and reviewed by The New York Times show that a Portuguese businessman, José Veiga, wrote reference letters on behalf of the president’s granddaughter to the condo association ahead of the sale. He called her “one of my best friends” and said she would be a “valued addition” to the Trump property.