An environmental advocacy group says in a report released Thursday that over 1.4 million rosewood logs from Nigeria worth $300 million were illegally sent to China after Nigeria's then-Environment Minister Amina Mohamed signed thousands of retroactive permits.

U.N. spokesman Stephane Dujarric said Mohamed, who is now the U.N. deputy secretary-general, "rejects any allegations of fraud."

He told reporters Thursday that Mohamed legally signed export certificates that were requested before the Convention on International Trade in Endangered Species added rosewood — also known as kosso — to a list of flora and fauna species in May 2016 that require a CITES certificate before logs can be legally exported.

The Washington-based Environmental Investigation Agency, known as EIA, said in the report that multiple sources told its undercover investigators that over $1 million was paid to top Nigerian officials to release wood stopped by Chinese authorities because there were no CITES certificates.

It said thousands of permits were ultimately signed by Mohamed in January 2017, just before she stepped down as environment minister to take up the U.N. post.

EIA said rosewood is coveted in China for furniture and over the past five years "exploding Chinese demand" has depleted forests across West Africa. As supplies in Gambia and Benin dwindled, it said Chinese traders moved to Nigeria, which had the largest untapped resource.

Since 2013, the advocacy group said, Nigeria has been transformed from a net importer to the world's largest exporter of rosewood logs, which is causing desertification, threatening national parks and imperiling the livelihoods of millions of people.

Dujarric said Mohamed's actions as environment minister "were intended to deal with the serious issue of illegal wood exportation." She instituted a ban on rosewood exports and set up a high-level panel "to find policy solutions to the crisis of deforestation in Nigeria," the U.N. spokesman said.

Dujarric said "the legal signing of export permits for rosewood was delayed due to her insistence that stringent due process was followed."

The allegations against Mohamed were first reported by the French newspaper Le Monde and Foreign Policy.

Foreign Policy reported Thursday that CITES "has shown no indication that it is satisfied by Mohamed's account ... and it intends to address Nigeria's conduct during a meeting of treaty signatories in Geneva from Nov. 27 to Dec. 1."

News from © The Associated Press, 2017