OPEC crude production climbed last month as Saudi Arabia spearheaded a recovery in Middle Eastern exports, according to a survey.

The group's daily output rose by 1.12 million barrels to 20.71 million barrels, with Saudi Arabia accounting for roughly half of the increase. Output still stands about 20% below pre-war levels, as the US-Iran conflict continues to disrupt shipping in the Persian Gulf.

Shell CEO Wael Sawan said at a conference in London this week that Middle Eastern oil shipments have recovered to about 80% of their pre-conflict level.

Saudi Arabia's pipeline exports to the Red Sea have largely returned to normal. At the same time, the kingdom has also ramped up exports through the Strait of Hormuz, its main pre-war export route. The survey showed Saudi daily production rose by 660,000 barrels to 7.17 million barrels, though it remains about 3 million barrels per day below pre-war levels.

Iraq posted the second-largest gain, with daily output up 350,000 barrels to 3.75 million barrels. Nigeria, Iran and Kuwait recorded smaller increases.

However, it remains unclear how long last month's production recovery can be sustained after a rise in attacks on oil tankers by Iran. The UK Maritime Trade Operations office has reported 10 attacks in the Strait of Hormuz so far this month. The strait is the main export channel linking the Persian Gulf to international markets.

The production survey is based on ship-tracking data, information provided by officials, and estimates from consultancies including Rapidan Energy Group, FGE NexantECA, Kpler Ltd. and Rystad Energy AS.