The European Commission is investigating possible manipulation of interbank lending benchmarks including the Euro Interbank Offered Rate (Euribor), the London Interbank Offered Rate (Libor) and the Tokyo Interbank Offered Rate (Tibor).

The EU watchdog has not disclosed the names of the banks being investigated. They could face fines up to 10 percent of their global revenues if found to have breached EU antitrust rules.

"Several banks have come forward with information to the Commission," said one of the sources, who declined to be identified because of the sensitivity of the matter. The person declined to provide more details.

The second person said there could be at least two banks, besides Deutsche Bank (DBKGn.DE), which had sought leniency under the European Commission's scheme to encourage whistleblowers.

(Reporting by Foo Yun Chee; editing by Rex Merrifield)

• A Permanent Economic Emergency