U.S. antitrust regulators said Friday they are closely monitoring oil markets for potential price-fixing or market monopolization, and they urged state attorneys general to assist in investigating unlawful conduct.

“Recent volatility in crude oil prices does not suspend either the antitrust laws or state consumer protection laws, and it does not authorize companies to manipulate retail prices or collude with their competitors,” said officials from the Justice Department and the Federal Trade Commission in a letter to states reviewed by CBS News.

“Business may not use market volatility as cover for anticompetitive practices, fraud, or any other lawlessness that harms Americans,” they added.

In the letter, Justice Department Associate Attorney General Stanley Woodward, who oversees the Antitrust Division, and FTC Chairman Andrew Ferguson also suggested that states could assist with policing price-gouging — an area in which the federal government does not have any enforcement authority.

“Although the Division and the Commission do not enforce any laws aimed specifically at price gouging rather than anticompetitive conduct, many States have also enacted laws specifically targeting price gouging during periods of market disruption or emergency, and we urge those states to review whether enforcement is warranted under those laws,” they added.