Citing people familiar with the talks, the Financial Times said Qatar's sovereign wealth fund, the Qatar Investment Authority (QIA), was in talks to acquire 5 percent to 7 percent of Greece's biggest lender.
'National Bank never had talks about selling a 5 to 7 percent stake in a non-pre-emptive rights basis,' the Greek source told Reuters.
He said such an issue would favour one shareholder above others.
The Qatar Investment Authority already owns slightly less than 1 percent in NBG. The source, who declined to be named, did not comment when asked if Qatar expressed any interest in raising its stake.
On Monday, National Bank of Greece denied what it called media reports it was planning to expand its capital. It said its position was strong.
Debt-choked Greece is trying to woo foreign investors and divest some state assets to help plug a huge budget gap.
The Financial Times said such an acquisition would help boost confidence in the Greek banking system, which is under pressure as a result of the sovereign debt crisis.
Greek Prime Minister George Papandreou told Canadian television earlier that sovereign wealth funds were eyeing stakes in Greek banks, but did not name a specific country, the Financial Times said. It added QIA was not immediately available for comment.
Last week, Papandreou urged Greek banks to consolidate.
(Reporting by Lefteris Papadimas; additional reporting by Jui Chakravorty in New York; writing by Ingrid Melander and Alister Doyle; editing by Andre Grenon) Keywords: GREECE QATAR/NBG (firstname.lastname@example.org +30 210 337 6438; Reuters Messaging: email@example.com) COPYRIGHT Copyright Thomson Reuters 2010. All rights reserved. The copying, republication or redistribution of Reuters News Content, including by framing or similar means, is expressly prohibited without the prior written consent of Thomson Reuters.