Oil prices have fallen again due to increasing doubts among investors that OPEC may not be able to sustain the agreed output-cut.

Down by 14 cents, Brent crude LCOc1 traded at $55.83 a barrel while US West Texas Intermediate (WTI) crude CLc1 slipped by 23 cents to reach $52.97, reported Reuters.

To revive the falling oil prices, OPEC decided to reduce their crude production by 1.8 million barrels a day for the first six months of 2017.

OPEC has published a report, indicating more than 90% compliance among its member countries in January.

"Overall, the oil market continued to be well-supplied due to a 6.5% increase in US production."

However, BMI Research pointed out that most of the output cut was performed by Saudi Arabia.

The second largest oil producing country after Saudi Arabia, Iraq achieved a compliance rate of around 40%.

Overall, the oil market continued to be oversupplied due to a 6.5% increase in US production.

The oil market is also concerned about the rising correlation among crude futures and US dollar.

Typically, oil prices and dollar exhibit inverse association as weaker dollar means cheaper crude imports. However, the value of US currency increased due to rising interest while oil prices have gained due to support from output-cuts.