VIENNA — OPEC countries failed Thursday to agree on measures to influence crude supplies and prices – a missed opportunity to show the resolve that for decades let them set how much consumers and industries worldwide would pay for gas, heating and related necessities.

At the same time, OPEC officials argued that the cartel was alive and well, scoffing at suggestions that its authority was eroding to the point where it will soon be negligible.

“Don’t take that (to mean) that OPEC is dead,” said Secretary General Abdulla al-Badri. “OPEC will be powerful, will be strong. OPEC is alive.”

But the decision to make no decision appeared more an illustration of lack of unity, particularly between OPEC rivals Saudi Arabia and Iran, whose deepening struggle for Mideast supremacy has for years been mirrored at oil meetings.

Iran was second only to the Saudis inside the Organization of the Petroleum Exporting Countries in terms of production before international sanctions over its nuclear program crippled sales. Now with a deal in place limiting its atomic prowess, sanctions have been lifted – and Tehran served notice even before the Vienna meeting that it intends to reach or surpass previous levels.

In part, the OPEC divide reflects growing political tensions between Shiite powerhouse and the Sunni-ruled desert kingdom, regional rivals that back opposite sides in the Syria’s war and the conflict in Yemen.

They broke off diplomatic relations earlier this year after Saudi Arabia executed a prominent Saudi Shiite cleric, a move that sparked protests in Iran and the storming of Saudi diplomatic posts.

Still, with the Saudis used to setting OPEC’s agenda, the main issue between the two in Vienna on Thursday appeared to be oil-related.

Since deciding in 2014 to squeeze out outside competition by flooding the market to drive down prices, the Saudis have pumped close to or above 10 million barrels a day – close to a third of OPEC’s total. That, plus resurgent output from Iraq and Iran, helped push down prices, with the desired effect of making shale production increasingly uneconomical.

But Saudi Arabia came to Vienna this time more focused on easing OPEC concerns of a further production increase that could reverse the upward price trend.