Oil prices rose by over $3 on Tuesday after shipping industry sources said oil loadings at Saudi Arabia’s Red Sea port of Yanbu had been suspended, and Libya halted operations at three oil fields, heightening concerns that disruptions to key oil supply routes could persist for weeks.

Brent crude futures were up $3.49, or 3.3%, at $109.20 a barrel at 1:20 p.m. ET (1720 GMT), while U.S. West Texas Intermediate futures rose $5.08, or 5.01%, to $106.46 a barrel.

If gains hold, both contracts are on track for their highest close in nearly four months.

Supply concerns have intensified after Iran-backed Houthi forces in Yemen launched fresh attacks on Saudi Arabia on Monday, while Gulf Arab states postponed planned discussions with Iran.

The latest strikes followed a Houthi attack on Saudi Arabia’s East-West Pipeline on Friday that forced the kingdom, the world’s largest crude exporter, to shut the key export route.

Further underscoring supply risks, shipping industry sources told Reuters on Tuesday that oil loadings at Saudi Arabia’s Red Sea export terminal in Yanbu had been suspended. The report came after sources said Riyadh had informed European customers that some late-September crude cargoes would be cancelled.

Andy Lipow, president of Lipow Oil Associates, said the cancellation of some Saudi crude shipments to Europe has strengthened expectations that European refiners will turn to U.S. supplies, helping lift WTI relative to Brent.

Traders have been buying WTI futures on bets that disruptions to Saudi exports will last longer than expected, Lipow said. Because U.S. refiners can readily switch between crude grades, demand for sweet crude such as WTI could increase, lending further support to prices, he added.

In Libya, separately from the Iran conflict, the National Oil Corporation (NOC) said operations at three oil fields were suspended after protesting members of the Petroleum Facilities Guard shut a valve on the Hamada-Zawiya crude export pipeline.

The Guard warned the shutdown could be expanded if its demands are not met. The NOC said it may declare force majeure if the valve remains closed or if additional fields are forced to halt production.

Meanwhile, continued attacks on energy infrastructure in Russia and Ukraine pushed U.S. diesel futures to a more than four-year intraday high on Tuesday, putting them on track for a record close.

“Fresh attacks by the Houthis targeting Saudi Arabia may be influencing oil market investors’ expectations about the severity and duration of the conflict,” said Hamad Hussain, senior climate and commodities economist at Capital Economics.

Saudi Arabia could exhaust crude available for export within days unless the East-West Pipeline resumes operations, according to buyers and traders. The pipeline strike threatens up to 4% of global oil supply.

U.S. Energy Secretary Chris Wright told CNBC on Tuesday, however, that oil should be flowing through Saudi Arabia’s vital East-West pipeline within days.

Goldman Sachs said in a note the latest repair assessments range from ‘very soon’ to eight weeks.

Supply Risks Mount

The attacks on oil infrastructure marked a significant escalation of the conflict and increased the probability of Brent rising above $120 a barrel, Goldman Sachs said, citing a scenario in which average Gulf oil output in 2027 remains 4 million barrels per day below pre-war levels.

Commodity vessel traffic through the Strait of Hormuz dropped to four on Monday, down from 10 a day earlier, preliminary data from Kpler showed on Tuesday.

Russia hit petrol stations in Kyiv on Tuesday and Ukraine struck a Russian oil refinery, as the warring sides carried on with strikes on each other’s energy targets despite an announcement by U.S. President Donald Trump that they had agreed to stop.

Half of Russia’s six top diesel-producing refineries were forced to significantly cut back or completely halt output in September due to damage sustained in drone attacks, according to Reuters calculations based on data from fuel market participants.

(Reporting by Siddharth Cavale in New York, Colleen Howe in Beijing and Anushree Mukherjee and Pranav Mathur in Bengaluru. Editing by Louise Heavens, Kirsten Donovan, Mark Potter, Nick Zieminski and Sanjeev Miglani)