Oil prices have fallen due to investors being doubtful that members of the Organisation of the Petroleum Exporting Countries (OPEC) will agree to freeze a deal to cut output, as well as a rise in US crude stocks.   

Brent crude futures dropped 72 cents at $50.07 a barrel, while US crude futures slipped 73 cents to $49.23 a barrel, Reuters reported. 

Iraq is the second-largest OPEC member and unwilling to participate in the proposed deal to cut output.

"The talking has to get louder and louder to attract any attention, because scepticism is on the rise and I think rightly so."

The OPEC members will approve the proposed oil output cut at a meeting in Vienna next month.

Traders and investors are less confident about the deal as Iran, Nigeria and Libya are already expected to be excluded, along with potentially Venezuela and Indonesia.

Saxo Bank senior manager Ole Hansen told the news agency: "The market is definitely in need of some kind of soothing words once again, but it's a 'cry wolf' thing. The talking has to get louder and louder to attract any attention, because scepticism is on the rise and I think rightly so."

Unless non-OPEC member Russia participates in the effort, Arab producers in the Middle East such as Saudi Arabia, Kuwait and the UAE, will be responsible to decide on the potential cut.

Data released by the American Petroleum Institute highlighted a rise in US inventories adding to the pressure on the oil market.