LONDON, U.K.: Oil prices surged above US$100 a barrel on Monday as escalating tensions between the United States and Iran, including plans for a naval blockade, heightened concerns over global supply disruptions.

Brent crude futures gained $6.52, or 6.9 percent, to $101.72 a barrel by 1306 GMT after settling 0.75 percent lower on Friday. U.S. West Texas Intermediate was up around $7, or 7.2 percent, at $103.55 after a 1.33 percent loss in the previous session.

President Donald Trump said on Sunday that the U.S. Navy would start blockading the Strait of Hormuz, raising the stakes after marathon talks with Iran failed to reach a deal to end the war, jeopardizing a fragile two-week ceasefire.

He added that the price of oil and gasoline could remain high through November's U.S. midterm elections, a rare acknowledgment of the potential political fallout from his decision to attack Iran six weeks ago.

"The announced U.S. blockade marks an admission that the ceasefire's central premise, at least as interpreted by the U.S., which was the reopening of the Strait, is untenable for now," said Erik Meyersson, analyst at Nordic bank SEB.

U.S. Central Command said that U.S. forces would begin implementing the blockade of all maritime traffic entering and exiting Iranian ports at 10 a.m. ET (1400 GMT) on Monday.

It would be "enforced impartially against vessels of all nations entering or departing Iranian ports and coastal areas, including all Iranian ports on the Arabian Gulf and Gulf of Oman," CENTCOM said in a statement on X.

U.S. forces would not impede freedom of navigation for vessels transiting the Strait of Hormuz to and from non-Iranian ports, it added.

While Trump said he would also block any vessels that paid Iran a toll, Tehran's ambassador to New Delhi said on Sunday that Indian tankers that transited through the Strait did not pay.

Iran's Revolutionary Guards said that any military vessels attempting to approach the Strait of Hormuz would be considered in violation of the ceasefire and be dealt with harshly and decisively.

The OPEC producer group lowered its forecast for world oil demand in the second quarter by 500,000 barrels per day, citing the impact of the war in the Middle East.

In a report on its website on Monday, OPEC said that crude production from OPEC+ members averaged about 35.06 million bpd in March, registering a monthly decline of 7.7 million bpd.

Physical crude barrels are trading at significant premiums to futures, with some grades already at record highs of about $150 a barrel.

"[If] President Trump does indeed back his blockade threat with actual boats, a convergence between the paper and physical markets may soon come," said RBC Capital Markets analyst Helima Croft.

Oil tankers are steering clear of the Strait of Hormuz ahead of the U.S. blockade on Iran, shipping data on LSEG showed.

However, three supertankers fully laden with oil passed through the strait on April 11, shipping data showed. They appeared to be the first vessels to exit the Gulf since the ceasefire deal was struck last week.

On Sunday, Saudi Arabia said it had restored full oil pumping capacity through the East-West pipeline to about 7 million barrels per day after damage to its energy sector from attacks during the Iran conflict.