Oil prices have faltered due to investors’ continued uncertainty ahead of Britain’s referendum this week on its withdrawal from the EU.

Brent crude August futures LCOc1 were down 42 cents and traded at $50.23 a barrel, while US crude’s expiring July front-month contract CLN6 was down 45 cents at $48.92 a barrel, Reuters reported.

Two opinion polls suggesting support for the UK staying in the EU had strengthened this week.

Nigerian media reported that the government and militants in the Niger Delta have signed a 30-day ceasefire to address demands.

"Recent days have shown just how quickly public opinion can shift."

This development also added a bearish signal to the market.

Militant attacks have recently disrupted crude oil exports in the country.

Commerzbank told the news agency: "There is probably too much confidence about the outcome of the Brexit referendum at present, recent days have shown just how quickly public opinion can shift."

In April this year, Saudi Arabia’s crude oil exports witnessed a fall despite high output levels.

Iran oil ministry’s news agency Shana reported that the country increased its crude export capacity at its main terminal on Kharg Island, which is potentially adding to supply.