S.Africa's Tannenbaum says defrauded Barwa-source

* Source says Tannenbaum admitted to forging documents

* Affidavit filed in Barwa UK court application

By Rebecca Harrison

JOHANNESBURG, July 2 (Reuters) - A South African businessman accused of orchestrating a 15 billion rand ($1.93 billion) fraud has admitted to forging documents to deceive Qatar's Barwa Real Estate BRES.QA, a source close to the matter said on Thursday.

The source, who asked not to be named, said Barry Tannenbaum had made the admission in a signed affidavit used by Barwa in a UK court application to freeze the assets of Dean Rees, a South African lawyer who the source said was linked to Tannenbaum.

The source was confirming an article in South Africa's Financial Mail weekly, which printed part of the affidavit on Thursday and said Tannenbaum had signed it.

"It is a legitimate document that has been signed by Barry," the source said when asked about the affidavit. "It was part of the application in the London High Court."

Reuters was not immediately able to obtain a copy of the document. Tannenbaum did not reply directly to emailed questions about whether he admitted to forging documents.

"No-one has accused me of having committed a specific crime," he wrote. Tannenbaum has denied wrongdoing in previous emails to Reuters. He did not answer a further email on Thursday asking for clarification.