(Bloomberg) -- OPEC and its allies gathered for a third successive day of meetings in Vienna to give the final sign-off to an oil-production increase.

Major producers outside the Organization of Petroleum Exporting Countries -- including Russia, Mexico and Kazakhstan -- will meet ministers from the cartel in the Austrian capital on Saturday to endorse a plan to add about 700,000 barrels a day of crude to the market starting next month. The non-members will approve the deal, which was sealed on Friday after a last minute compromise between Saudi Arabia and Iran, said four delegates.

"I hope that today in the meeting with our friends in non-OPEC we as well will reach the same conclusion” on a production increase, United Arab Emirates Energy Minister Suhail Al Mazrouei told reporters on Saturday. “I am confident that it is not going to be a difficult meeting."

Friday’s agreement was a fudge in the time-honored tradition of OPEC, committing to boost output without saying which countries would increase or by how much. It gives Saudi Arabia and Russia -- holders of the largest spare capacity in the group -- the flexibility to respond to disruptions and moderate prices at a time when U.S. sanctions on Iran and Venezuela threaten to throw the oil market into turmoil.

The terms of the deal were rather convoluted. OPEC agreed on a “nominal” production increase of 1 million barrels a day, said Saudi Energy Minister Khalid Al-Falih. In reality, the accord will add a smaller amount of oil to the market because a number of countries are unable to raise their output. The official communique from the meeting didn’t mention any specific production numbers, instead pledging that the group would focus on restoring its output cuts to the level originally agreed in 2016.

Lack of Confidence

Some traders were far from confident that such an agreement will meet the multiple challenges OPEC faces. The situation in Venezuela is volatile, with a wide range of predictions of how much further its production could slump as its industry unravels. There are also growing signs that the renewed U.S. sanctions on Iran could have a larger impact than the 1 million-barrel-a-day reduction in exports seen in 2012.

Iran doesn’t believe its customers will get waivers from the U.S. government that would allow them to continue crude purchases, Oil Minister Bijan Namdar Zanganeh said in a Bloomberg television interview on Friday. American officials are said to have asked Japan to completely halt oil imports from Iran, going beyond the cuts demanded during the Obama-era sanctions.

Crude prices surged on Friday following the vaguely worded OPEC agreement. West Texas Intermediate crude jumped 4.6 percent to $68.58 a barrel, the biggest gain in six months.

U.S. President Donald Trump, whose tweets played a part in prompting Saudi Arabia to push for a production increase, indicated on Friday that he’ll be watching the progress of their new agreement closely.

“Hope OPEC will increase output substantially,” Trump said on Twitter. “Need to keep prices down!”

--With assistance from Grant Smith, Laura Hurst, Elena Mazneva, Salma El Wardany, Julian Lee, Golnar Motevalli and Annmarie Hordern.

To contact the reporters on this story: Wael Mahdi in Kuwait at wmahdi@bloomberg.net;Javier Blas in Vienna at jblas3@bloomberg.net;Nayla Razzouk in Dubai at nrazzouk2@bloomberg.net

To contact the editors responsible for this story: James Herron at jherron9@bloomberg.net, Amanda Jordan

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