An environmental advocacy group claims 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.

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

Dujarric told reporters Thursday that Mohamed legally signed export certificates requested before the Convention on International Trade in Endangered Species added rosewood to a list of species that require a CITES certificate before logs can be legally exported.

The Washington-based Environmental Investigation Agency said in the report released Thursday 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.