NEW YORK (Bloomberg) — Exxon Mobil Corp., the world’s biggest publicly traded oil company, and four other US gas retailers must face a lawsuit accusing them of conspiring to drive up the price of gasoline, a federal judge ruled.Exxon, Marathon Oil Corp., Citgo Petroleum Corp. and US affiliates of Royal Dutch Shell Plc and BP Plc are accused in the complaint of intentionally limiting the available gasoline supply, driving up prices and boosting profits, U.S. District Judge Amy St. Eve in Chicago said.

“Facts consistent with these allegations could establish that defendants unjustly enriched themselves or acted deceptively or unfairly,” St. Eve said, rejecting the companies’ request that she dismiss the lawsuit, which seeks class action status on behalf of all affected Illinois consumers. Some claims in the complaint were dismissed.

The ruling allows Chicago-area plaintiffs Michael and Rebecca Siegel, who filed the complaint under Illinois’ consumer fraud statute, to demand evidence and testimony from the companies to buttress their claims, including records detailing the reasons for their production and pricing decisions.

Larry Drury, a Chicago lawyer representing the Siegels, declined to say how much money he is seeking on behalf of Illinois consumers.

“Class certification is on the agenda here,” Drury said, referring to court approval of class action status, which would allow the Siegels to represent all similarly situated Illinois consumers. Class, or group status, would give the plaintiffs more leverage to negotiate a favorable settlement or win at trial by pooling legal resources.

St. Eve dismissed plaintiff claims that the companies used Hurricane Katrina, which struck the US gulf coast in August 2005, as a pretext for artificially boosting retail prices. The judge said Drury may refile those claims with additional facts.

“It’s a good possibility that we’ll re-plead those particular allegations,” he said.

The ruling allows Drury to press claims that the companies decreased gasoline production during peak usage periods.

“Summer’s coming along. We’ll be watching gas prices again,” he said.

Neil Chapman, a Houston-based spokesman for London-based BP, said he wasn’t aware of the ruling and declined to comment.

Ann Peebles, a spokeswoman for Netherlands-based Shell, and Linda Casey, a spokeswoman for Houston-based Marathon, also declined to comment.

Fernando Garay, a spokesman for Houston-based Citgo, a unit of Caracas-based Petroleos De Venezuela SA, and Exxon Mobil spokeswoman Prem Nair declined to immediately comment.

Exxon Mobil shares fell 15 cents to $75.56 in New York Stock Exchange composite trading.