Taiwan's Fair Trade Commission (FTC) has fined Apple US$666,700 for restricting the prices charged by local telecom carriers for their iPhone contracts, the first time Apple has been fined for such practices.

The regulator said that Apple Asia, a unit of the Cupertino-based company, required carriers to obtain its permission before setting contract prices on iPhones, which it found to be in violation of Taiwan's free-trade laws.

Apple Asia also told carriers to alter service contract prices and subsidy prices, according to an FTC statement on Wednesday, leading to the fine of T$20 million.

Officials with Apple Asia could not be reached for comment on Thursday.

The three carriers, Chunghwa Telecom, Taiwan Mobile and Far EasTone Telecommunications had all obtained reseller rights under their contracts with Apple, which gave them the right to set prices, FTC spokesman Sun Lih-chyun said.

Apple has been facing challenges in the rapidly-evolving marketplace for the smartphones in which it once held a commanding lead.

The company recently reported that it signed a long-awaited deal with China Mobile, China's largest telecom carrier, to sell its iPhones, raising hopes that it may make significant inroads in the world's largest smartphone market.

(Reporting by Michael Gold and Clare Jim; Editing by Matt Driskill).