Oil prices on Friday hit $66 a barrel, setting a fresh six-month high and heading for their biggest monthly gain in more than 10 years, following Opec’s upbeat comments about oil demand in Asia at its meeting this week.

Abdalla El-Badri, Opec’s secretary general, said prices could rise to $70-$75 a barrel by the end of the year. “The outlook is improving,” Mr El-Badri said over breakfast. But added: “The fundamentals are still weak.”