Antitrust officials are examining whether OPEC has violated US competition laws, as Congress intensifies its political pressure in response to the surge in oil prices.

The Federal Trade Commission (FTC) is reviewing court rulings, dating back more than two decades, that give OPEC sovereign immunity from US antitrust laws.

The FTC is facing increasingly urgent calls from senior members of Congress to take action against the oil cartel. The House Judiciary Committee will hold hearings on the possibility of antitrust action next week.