RIYADH, Sept. 17 (Xinhua) -- Saturday's drone attacks on oil production facilities in eastern Saudi Arabia have raised global concerns over the broader Middle East, while global oil prices have surged.

On Tuesday, Organization of the Petroleum Exporting Countries (OPEC) calculations showed that the price of the OPEC basket of fourteen crudes closed at 66.43 U.S. dollars a barrel on Monday, an over-10-percent rise compared with 60.02 dollars last Friday.

U.S. President Donald Trump said Monday "it's looking that way" that Iran was behind the recent attacks on Saudi Arabia's key oil facilities.

"We're having some very strong studies done, but it's certainly looking that way at this moment ... As soon as we find out definitively, we'll let you know," Trump told reporters at the White House.

When asked if he will meet with Iranian President Hassan Rouhani on the sideline of the United Nations General Assembly next week, Trump said "I have no meeting scheduled."

U.S. Secretary of Defense Mark Esper said in a series of tweets on Monday that he had spoken to Crown Prince of the Kingdom of Saudi Arabia, Mohammad bin Salman, and Iraqi Minister of Defense (Najah) al-Shammary over the weekend.

"The United States military, with our interagency team, is working with our partners to address this unprecedented attack and defend the international rules-based order that is being undermined by Iran," he said.

Iranian Foreign Ministry spokesman Abbas Mousavi on Monday rejected U.S. claims that Iran is behind the attacks, calling them "baseless."

On the issue of who is behind the attacks, Chinese foreign ministry spokesperson Hua Chunying said in a press release on Monday that "We don't think it is responsible to assert who is responsible before a conclusive investigation."

"China is against any move that will aggravate conflict," Hua said. "We call on relevant sides to refrain from actions leading to escalation of the tensions in the region. We hope all parties will exercise restraint and jointly safeguard the peace and stability in the Middle East."

The attacks have ratcheted up the already tense situation in the Middle East caused by U.S. maximum pressure policies on Iran, including a total oil trade ban.

There are fears that the rising tensions could spark a military conflict in the Gulf between Iran and the United States or Saudi Arabia.

The drone attacks on two facilities of Saudi Arabia's state oil company Saudi Aramco in the east of the country resulted in fires that were later controlled.

Saudi Arabia saw production cut by 5.7 million barrels, or about 50 percent of the company's daily production after Saturday's attacks, according to Aramco.

United Arab Emirates Energy Minister, Suhail Al Mazrouei, said Monday that the UAE, as an OPEC member, is ready to support Saudi Arabia by providing additional capacity.

"We have certain capacity that we can put into the market," said Mazrouei in statements.

He said that it is premature to call an emergency OPEC meeting without the request of Saudi Arabia, stressing the UAE's commitment to OPEC's decisions and that it will not take any related action without the organization's approval.