Oil capped its longest rally in more than a year as Iran threatened to block transportation through the Strait of Hormuz and confidence among U.S. consumers beat expectations in December.

Crude settled at the highest level in six weeks after Iran’s official Islamic Republic News Agency cited Vice President Mohammad Reza Rahimi as saying the country would bar shipments through the strait if sanctions are imposed on its oil exports. Futures also rose as the Conference Board’s index reached the highest level since April.

Oil for February delivery rose $1.66, or 1.7 percent, to $101.34 a barrel on the New York Mercantile Exchange, the highest settlement since Nov. 16. Crude has advanced for six consecutive sessions, the longest rally since a period ended Nov. 8, 2010. Futures have climbed 11 percent this year after increasing 15 percent in 2010.

Brent oil for February settlement gained $1.31, or 1.2 percent, to $109.27 a barrel on the London-based ICE Futures Europe exchange. The European contract’s premium to crude in New York was $7.93 a barrel, the smallest differential based on settlement prices since Jan. 20.

Markets in New York and London were shut because of the observance of Christmas and will be closed on Jan. 2 for New Year’s Day.

Oil surged on what is one of the year’s slowest trading days. Volume on the Nymex totaled 190,429 contracts as of 3:43 p.m. Volume was 167,547 on Dec. 23, the lowest level since Dec. 26, 2008, and down 73 percent from the average of the past three months. Open interest was 1.31 million contracts.

“A lot of people are on vacation this week,” said Peter Beutel, president of trading advisory company Cameron Hanover Inc. in New Canaan, Connecticut. “Volume will remain light until Jan. 3. We can expect to see exaggerated price moves until things pick up next week.”

About 15.5 million barrels of oil a day, or a sixth of global consumption, passes through the Strait of Hormuz between Iran and Oman at the mouth of the Persian Gulf, according to the U.S. Energy Department.

Iran is attempting to “distract attention” from its nuclear program by threatening to block oil shipments through the strait, Mark Toner, a State Department spokesman, said at a briefing today in Washington.

Oil increased 2.4 percent in New York on Dec. 13 after Iran announced plans for military exercises in the strait, a critical waterway for crude shipments, as the U.S. and its allies threatened to bolster sanctions.

Iran pumped 3.56 million barrels a day of oil in November, according to Bloomberg News estimates, trailing only Saudi Arabia among members of the Organization of Petroleum Exporting Countries. Iran is trying to reduce its dependence on fuel imports.