Vienna: Opec leaders announced a surprise output cut on Wednesday, in response to falling oil prices.

Opec President Chakib Khelil said the group would cut oil output by about half a million barrels per day (bpd) from July’s level over the next forty days.

"I think if you do your own calculation properly, it will be a lowering of production by about 520,000 barrels per day," Khelil said.

Immediately after the announcement, oil prices went up by a dollar.

The decision to return to a production ceiling of 28.8 million bpd, which was in effect a year ago, was made after nearly five hours of debate.

Opec ministers were expected to leave the output targets unchanged.