NEW YORK CITY, New York: Crude oil prices climbed about four percent on September 24, with Brent heading for its highest close in more than a week as fresh missile attacks on Saudi Arabia added to concerns over Middle East supplies and efforts to end the U.S.-Iran war made little progress.

Brent futures gained US$4.10, or four percent, to $107.18 a barrel at 11:09 a.m. EDT (1509 GMT). U.S. West Texas Intermediate crude rose $3.66, or four percent, to $95.82.

Brent, which had already risen about eight percent over the previous two days, was on course for its highest close since September 15. WTI was heading for its first gain in seven days after losing about 13 percent over the preceding six sessions.

Saudi Arabia intercepted six ballistic missiles launched by Yemen's Iran-backed Houthis on Thursday, preventing attacks on the southern province of Taif and the Yanbu area on the Red Sea, according to the Saudi-led coalition in Yemen.

The attacks came as diplomatic efforts to end the U.S.-Iran war remained at an impasse. A senior Iranian official told Reuters on September 23 that the two countries were still far apart on how to end the conflict, but that diplomacy must continue. Iran's president told the U.N. General Assembly that Tehran would never surrender to U.S. pressure.

Washington has also expanded its economic campaign against Iran. Iranian flights to neighboring Gulf countries, including Dubai, appeared to have been canceled on September 24 after a U.S. deadline for global companies to stop working with Iranian airlines passed.

The deadline forms part of a campaign President Donald Trump calls "economic D-Day." The United States has shifted toward targeting companies in third countries that conduct business with Iranian firms through measures known as "secondary sanctions".

Iran warned on September 23 that it would retaliate against neighboring countries that complied with the U.S. flight ban by rendering their airports "unusable".

Separately, Saudi Arabia has been increasing crude volumes through its East-West Pipeline to the Red Sea export hub of Yanbu. Tanker loadings had not yet resumed, according to industry sources, satellite imagery and shipping data.

Diesel Prices and Export Concerns

Record-high diesel prices have prompted high-level discussions between the European Union and the United States over a reported U.S. proposal to restrict diesel exports.

Politico reported that Washington was preparing a 90-day export ban ahead of November's midterm elections, although U.S. Energy Secretary Chris Wright disputed the report. Analysts and market watchers have warned that a ban could worsen global supply pressures rather than lower energy prices.

U.S. diesel futures rose more than five percent in late-morning trading on September 24.

The premium of Brent crude over WTI also reached its highest level since May for a second consecutive day. A wider premium makes it more economical to ship U.S. crude overseas, although higher tanker-chartering costs have weighed on exports.

U.S. crude exports averaged 3.3 million barrels per day in the week ended September 18, according to the Energy Information Administration, compared with a weekly record of 6.4 million barrels per day in April, when shipping costs were much lower.