NEW YORK ( TheStreet) -- The Justice Department is stepping up its probe into whether tech heavyweights who purchased a large portfolio of Nortel patents could use them to unfairly hurt smartphones that run Google's ( GOOG) Android operating system, according to a published media report.

The report, published on The Wall Street Journal's Web site, cited anonymous sources familiar with the situation.

The companies that bought the patents include Apple ( AAPL), Microsoft ( MSFT) and Research In Motion ( RIMM).

The group purchased 6,000 patents from now-bankrupt Nortel for $4.5 billion.

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This article was written by a staff member of TheStreet.