Ahmed Zaki Yamani, a long-serving oil minister in Saudi Arabia who led the kingdom through the 1973 oil crisis that shattered the West and once found himself held hostage by the assassin Carlos the Jackal, died Feb. 23 in London. He was 90.

Saudi state television reported the death but did not give a cause.

Known for his Western-style business suits and soft-spoken, measured tones, Mr. Yamani helped Saudi Arabia command a dominating presence in the Organization of the Petroleum Exporting Countries from its birth. The kingdom remains a heavyweight in OPEC even today and its decisions ripple through the oil industry, affecting prices from the barrel down to the gasoline pump.

“To the global oil industry, to politicians and senior civil servants, to journalists, and to the world at large, Yamani became the representative, and indeed the symbol, of the new age of oil,” author Daniel Yergin wrote in “The Prize” (1990), a history of the oil industry. “His visage, with his large, limpid, seemingly unblinking brown eyes and his clipped, slightly curved Van Dyke beard, became familiar the planet over.”

Mr. Yamani, a Harvard-trained lawyer, became oil minister in 1962 and would lead the ministry until 1986. He served a crucial role in the nascent oil cartel OPEC as producers around the world began to try to dictate prices to the world market previously dominated by the economic policies of Western nations.

Mr. Yamani was the first Saudi representative on OPEC’s board of governors in 1961. From his position, he became known not for the hysterics that accompanied years of turmoil across the wider Middle East, but an ever-calm negotiating style that Saudi ministers after him sought to mimic.

But that style for an oil kingpin known by the honorific “the Sheikh” would be tested by the times, which included upheaval in the global energy market. That was especially true in the 1973 Middle East war, in which Egypt, Syria and their allies launched a surprise attack on Israel on the Jewish holy day of Yom Kippur.

When President Richard M. Nixon moved to support Israel, Arab producers in OPEC agreed to cut their supply by 5 percent a month. When Nixon continued his support, the decision gave birth to what would become known as the “oil weapon” — a total embargo on the United States and other countries, engineered by Mr. Yamani.

Prices in the United States would rise by 40 percent, leading to gasoline shortages and long lines at the pump. Oil prices globally would quadruple, leading to the wealth now seen across the Arab states of the Persian Gulf today.

“The Arab oil [embargo] was meant, and I was behind it, not to hurt the economy, just to attract the international public opinion that [there] is a problem between the Palestinians and the Israelis,” he told CNN in 2010. He added that he did not regret the embargo, but had reservations about OPEC’s later efforts to set prices, which he called “a mismanagement of power.”

In 1975, Mr. Yamani found himself twice at major moments in history.

He stood just outside the room when a nephew of King Faisal assassinated the monarch in March. In December, he was among those taken hostage at OPEC headquarters in Vienna, in an attack led by Carlos the Jackal. Three people were killed and dozens of others were seized, including 11 OPEC ministers, before all the hostages and pro-Palestinian militants were released. (One of the militants, Anis Naccache, died Feb. 22 at age 69 after being hospitalized for covid-19.)

Afterward, Mr. Yamani described Carlos, a Venezuelan whose real name is Ilich Ramírez Sánchez, as a “ruthless terrorist who operates with coldblooded, surgical precision.” From that moment on, Mr. Yamani traveled with an entourage of bodyguards everywhere he went.

After the 1973 oil crisis, Mr. Yamani also led the Saudi takeover of the Arabian American Oil Company, gradually wresting control of a consortium of American companies that had extracted the kingdom’s oil for decades. Now known as the Saudi Arabian Oil Company, or Aramco, the company is a major employer for the kingdom and its main source of revenue.

In 1986, King Fahd of Saudi Arabia dismissed Mr. Yamani with a terse statement carried by the state-run Saudi Press Agency. At the time, it was believed that Mr. Yamani disagreed with the king in his insistence that OPEC work out a permanent system of production quotas and that the kingdom would be given a bigger share of the total. Saudi Arabia ultimately went along with another interim arrangement.

Ahmed Zaki Yamani was born in Mecca on June 30, 1930, when camels still roamed the streets of Saudi Arabia’s holy city. His father and grandfather were religious teachers and Islamic lawyers.

Mr. Yamani completed his education abroad, receiving a bachelor’s degree from King Fuad I University in Cairo in 1951, a master’s degree from New York University in 1955 and graduating from Harvard Law School in 1956. He started a law firm in Jiddah, a port city on the Red Sea, and worked as a legal adviser to the Saudi government before becoming oil minister.

After his dismissal, he founded the Centre for Global Energy Studies, a London-based consulting firm.

He had three children from his first marriage, to Laila Sulleiman Faidhi, which ended in divorce. In 1975 he married Tamam al Anbar, with whom he had five children. Complete information on survivors was not immediately available.

— Associated Press