Saudi Oil Minister Ali al-Naimi on Tuesday gave no sign whether OPEC would agree this year's second output rise when it meets next week, but confirmed that the kingdom had boosted production to 9 million barrels per day (bpd).

"When we meet on the fifth we will look at all the information available, and decide accordingly, on whatever the information tells us about supply, demand, inventories," Naimi told reporters in Singapore, where he is due to speak at an energy conference on Wednesday.