ST PETERSBURG: Talks between OPEC and its allies next month over whether to extend their global oil output cut deal will be complicated by uncertainties over Iran and Venezuela's stance, Kazakh Energy Minister Kanat Bozumbayev said.

The Organization of the Petroleum Exporting Countries and other large oil producers, including Russia and Kazakhstan, will meet in Vienna on July 1-2 to discuss whether the oil output deal, which expires after June 30, should be continued.

"I think it won't be easy," Bozumbayev told reporters about the forthcoming talks, in comments cleared for publication on Monday.

"(There are) different positions. Some countries, like Iran, (there are) sanctions. Venezuela. Will they want to or not, it's hard (to say)," he said.