WASHINGTON (Reuters) -- The Supreme Court Monday agreed to consider an appeal by the largest U.S. telephone carriers seeking the dismissal of a class-action antitrust suit against them.

The high court granted the companies' petition to review an appeals court ruling that held the class-action suit filed against Verizon Communications (Charts), BellSouth (Charts), Qwest Communications International (Charts), and AT&T (Charts) could proceed even without evidence to back up claims of an anti-competitive conspiracy.

The Supreme Court will hear arguments in the case and then issue a decision during its upcoming term, which begins in October.

Separately, the Supreme Court on Monday also refused to consider an appeal by U.S. antitrust authorities who wanted to get antitrust charges reinstated against drug maker Schering-Plough (Charts).

The justices rejected a request by the Federal Trade Commission (FTC) to review a U.S. appeals court ruling that rejected an earlier finding by the FTC that Schering-Plough had illegally kept cheaper versions of its blood pressure drug K-Dur off the market.

In other decisions Monday, the Court said it would hear an appeal by forest products company Weyerhaeuser (Charts) of a $78.7 million judgment against it for monopolizing and trying to monopolize the market in the Pacific Northwest.

The justices agreed to review a U.S. appeals court ruling that upheld the judgment against the company for violating federal antitrust law and engaging in predatory conduct. Ross-Simmons Hardwood Lumber, a company that went out of business in 2001, blamed its failure on Weyerhaeuser and brought the lawsuit.

The Court is expected to decide the case in October.

And the Supreme Court said it would hear an appeal by a dozen states, three cities and a number of environmental groups seeking to force the U.S. government to regulate carbon dioxide emissions from cars and trucks.

The justices agreed to review a U.S. appeals court ruling that the U.S. Environmental Protection Agency (EPA) does not have the power to regulate the vehicle emissions blamed by most scientists for global warming.

The Bush administration, ten other states and a group representing electric generating companies opposed the appeal.

The high court will hear arguments and then issue a decision in the case during its upcoming term that begins in October.

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