The meeting of petroleum exporting countries to discuss an output freeze started in Doha, the Russian Energy Ministry posted in its official Twitter account.
The start of the meeting has been delayed by over six hours.
Saudi Arabia demanded on Sunday that Iran join a global deal on freezing oil output, jeopardizing the chances of an agreement between OPEC and non-OPEC producers that was supposed to prop up the price of crude.
Some 18 countries, including Russia, had been due to meet on Sunday morning in the Qatari capital of Doha to rubber-stamp a deal to stabilize output at January levels until October 2016. But the meeting was postponed after OPEC's de facto leader Saudi Arabia told participants it wanted all OPEC members to take part in the freeze, according to OPEC sources.
Riyadh had earlier insisted on excluding Iran from the talks because Tehran had refused to stabilize production, seeking to regain market share after the lifting of Western sanctions against it in January.
With the deal running into trouble, oil ministers in Doha met with the Qatari emir, Sheikh Tamim bin Hamad al-Thani - who was instrumental in promoting output stability in recent months.
A new draft of a deal to freeze oil output that is to be agreed later on Sunday in Doha has a line saying all OPEC members should be part of the agreement, industry sources said. The change appears to be a major obstacle for clinching a binding deal, given that OPEC member Iran had decided not to send representatives to the meeting, Reuters reports.
Analysts believe that the agreement of the largest exporters to freeze oil production will not have an impact on the market. However, it may seriously affect the oil prices, according to analysts of Bank of America and Saxo Bank.
The Doha negotiations are attended by representatives of 18 countries - OPEC members (except for Iran and Libya), as well as Russia, Mexico, Colombia, Oman, Kazakhstan, Azerbaijan and Bahrain.
