U.S. antitrust regulators gave Apple approval to buy certain assets to be sold by bankrupt telecom maker Nortel Networks Corp, the Federal Trade Commission said on Thursday.

Apple Inc, Intel Corp, Google Inc and Ericsson are interested in Nortel's portfolio of about 6,000 patents and patent applications. They are to be sold in an auction starting on Monday.

The patents cover wireless, data and optical networking, voice, Internet, semiconductors and other technologies.

Apple and Google are believed to be most interested in patents having to do with the latest wireless technologies, such as 4G and LTE.

The Justice Department had been looking at Apple's interest in the Nortel assets and was also reviewing Google's $900 million stalking horse opening bid, a source told Reuters in early June.

The FTC announced the approval in a listing that it puts out several times a week.

Nortel, which filed for bankruptcy in January 2009, has already sold most of its physical assets.

(Additional reporting by Alastair Sharp; editing by John Wallace)