Washington ? The Bush administration’s decision to buy oil for the nation’s strategic petroleum reserve last year, as oil prices were climbing, raised U.S. energy costs without significantly improving the nation’s energy security, a report by Senate Democrats said Wednesday.

Although the administration last year added 41 million barrels of oil to the reserve, U.S. energy companies cut back comparably on their own oil inventories, resulting in no net increase in nationwide oil supplies, said the report by the Democratic staff of the Senate Permanent Subcommittee on Investigations.

The strategy “appears to have backfired,” said Sen. Carl Levin, D-Mich., the subcommittee’s top-ranking Democrat. His staff’s 268-page report on the strategic oil reserve follows a year-long inquiry, most of it done while Levin was the subcommittee’s chairman.

Energy Secretary Spencer Abraham rejected the report’s conclusions, saying he did not believe the U.S. strategy affected prices.

Some industry analysts challenged the report’s conclusion, saying the escalating tensions over Iraq created a strong reason for increasing the oil stockpile.

“With the current Iraqi situation, the value of the strategic petroleum reserve is priceless,” said Adam Sieminski, an energy analyst with Deutsche Bank in London.

The administration’s error is in failing to use the oil stockpiles now, Sieminski said, to increase supplies and lower current oil prices, which have risen by more than 60 percent in the past year. “They keep waiting for some sign from heaven,” he said.

In November 2001, President Bush set a goal of increasing the reserve from about 550 million barrels to its full capacity of 700 million barrels, about a 45-day supply. Before that, the Energy Department had deferred purchases for the reserve when prices were moving higher.