A bill to toughen federal safety regulation of oil and gas pipelines passed the Senate late Monday only a few hours after a Republican senator opposed to government regulation dropped his opposition to the measure.

The bill is an attempt to close gaps in federal safety regulations exposed by a deadly gas pipeline rupture near San Francisco last year, as well as a spate of other recent gas explosions and oil pipeline spills. It would authorize more federal safety inspectors, increase penalties for violations and require pipeline companies verify their records on pipelines' physical and operational characteristics and establish maximum operating pressures based on the verified information.

Under the bill, federal regulators could order that automatic shutoff valves be installed on new pipelines so leaks can be halted sooner. And it directs regulators to determine whether mandatory inspections of aging pipelines in densely populated areas should be expanded to include lines in rural areas. It would be paid for by industry fees.

Federal accident investigators found that officials for Pacific Gas and Electric Co. didn't know that a large transmission line under a subdivision in San Bruno, Calif., was made with short pieces of inferior pipe welded together until after the line ruptured, igniting a pillar of fire and killing eight people. The company's records for the half century old line were inaccurate and the strength of the pipe hadn't been adequately tested.

People "shouldn't have to worry about streets exploding under their feet because of lax safety regulations," Sen. Dianne Feinstein, D-Calif., said in a statement. "Aging infrastructure demands proper regulation to save lives, and that's the path on which this bill sets us."

The bill was approved under unanimous consent procedures with no roll call vote or debate after Sen. Rand Paul of Kentucky abruptly dropped his hold on the measure. Senate Majority Leader Harry Reid, D-Nev., simply read the bill's title, asked that it be accepted and it was done.

The Senate Commerce, Science and Transportation Committee approved the bill in May without opposition. The bill is supported by the industry's major trade associations _ the Interstate Natural Gas Association of America, the American Gas Association and the Association of Oil Pipelines _ as well as the Pipeline Safety Trust, a safety advocacy group.

Paul had been holding up passage of the bill for months. The lone senator opposed to the measure, he told the bill's supporters in private meetings that his opposition was based on a philosophical objection to new regulation rather than any particular concern with the provisions of the bill.

On Monday, Paul said in a statement that he had dropped his opposition because the bill's sponsors had agreed to incorporate an amendment regarding safety testing of older pipelines. A spokeswoman for Paul, Moira Bagley, said she was unable to provide a copy of the amendment, but an aide to Reid confirmed it was added to the bill.

"I have found a way to address the problems more thoroughly through these regulations, while limiting their scope and unnecessary red tape," Paul said in a statement. "My proposal will be unanimously passed and accepted by both sides, further proving that my actions have enriched this legislation."

Paul, a tea party ally and anti-tax activist, was elected to the Senate last year in part on the strength of his opposition to new federal regulations.

Two House committees have unanimously approved separate pipeline safety bills that are similar to the Senate bill. Differences between those measures are expected to be worked out in the coming weeks, with a single bill brought to the House floor before the end of the year.