U.S. commercial crude oil inventories increased last week but gasoline reserves continued to fall, the Energy Department said Wednesday in its weekly petroleum report.

In the week ending April 20, the nation's commercial crude oil inventories rose by 2.1 million barrels to 334.5 million. That was defying analysts' expectation of a decline of 1.2 million barrels.

Gasoline reserves, however, dropped by 2.8 million barrels last week to 194.2 million. Analysts were forecasting an increase of 200,000 barrels.

Stockpiles of distillate fuels, which include heating oil and diesel fuel, were flat at 117.3 million barrels. Heating oil inventories fell last week while diesel stocks increased.

The department also said that retail gasoline prices have shown "extraordinary strength" since late January and that the upcoming 2007 summer driving season is likely to see sustained high gasoline prices.

Factors that could support such a scenario include: delays in refinery maintenance programs; tight gasoline supplies in Europe; strong gasoline demand; and geopolitical tensions in Iran, Nigeria, and Venezuela. That, along with OPEC production cuts, may contribute to tightening global gasoline markets, said the department.

The figures for commercial crude oil inventories do not include the U.S. Strategic Petroleum Reserve, which currently holds crude oil of about 6.89 million barrels.