Google chief Eric Schmidt says he won't resign as a director at Apple, despite an inquiry by the US Federal Trade Commission (FTC) into how his position affects competition between the two technology firms.

Schmidt and former Genentech CEO Arthur Levinson both sit on the boards of the two companies, which are rivals in the smartphone market where Apple's iPhone goes head-to-head with handsets that use Google's Android platform, such as the T-Mobile G1.

The FTC inquiry has been prompted by US law, which states that an individual can't sit on two boards if its decreases competition between the companies.

"If there are issues on competitiveness, I recuse myself," Schmidt added. He also said that he leaves the Apple boardroom during any discussion about the iPhone and that Google doesn't see Apple as a primary competitor.