Credit: Joe Raedle/Getty Images

(CNN)-- Oil prices rose to more than $90 a barrel for the first time in over a month, as the conflict between the United States and Iran escalated, resulting in the deaths of three American soldiers and the targeting of an oil tanker.

Brent crude, the global benchmark for oil prices, rose to its highest level since June 11, before paring gains to trade up about 1% at $88.94 a barrel. West Texas Intermediate, the US benchmark, also rose less than 1% to $82.26 a barrel.

Brent crude posted gains of nearly 16% over the past week, its biggest weekly increase since April, while European natural gas prices, according to Deutsche Bank, recorded their highest closing level since March.

Global energy prices continue to rise after the ninth consecutive night of US strikes against Iran. The crew of a ship that was targeted on Monday near the Strait of Hormuz was forced to evacuate, according to the UK Maritime Trade Operations (UKMTO).

In the United States, the average price of a gallon of gasoline reached $4 on Monday, only the second time since the war with Iran disrupted global oil supplies.

According to the American Automobile Association (AAA), the national average price was $4 per gallon, after first exceeding that level on March 31, a month after the conflict erupted.

The national average price for regular gasoline was $2.98 per gallon before the fighting broke out, which brought most oil flows through the Strait of Hormuz, one of the world's most important maritime energy trade routes, to a halt.

Prices rose to a four-year high of $4.56 per gallon in early May, before retreating on hopes that negotiations between Iran and the United States would reopen the waterway and allow stranded oil tankers in the Arabian Gulf to continue sailing.

The United States and Iran signed a memorandum of understanding on June 14 to cease hostilities, pushing gasoline prices back down to below $4 per gallon within a few days.

But prices at the pump rose again after Iran resumed attacking ships trying to leave the strait, and the US responded by imposing a blockade on Iranian ports. The average price increased by about 13 cents per gallon over the past week.

Despite this, the average gasoline price in about half of US states remains below $4 per gallon. Indiana records the lowest average at $3.35 per gallon, while California is the most expensive with an average of $5.49 per gallon. The average price also exceeds $5 per gallon in both Washington and Hawaii, according to AAA data.

Tom Kloza, an independent oil market analyst and consultant at Gulf Oil, said gasoline prices will not decline in the near future, noting that the recent rise in gasoline futures points to an additional increase of between 10 and 25 cents per gallon in the coming week. He said: "This increase is already a done deal."