Light oil prices have been trading at over $73 a barrel as the dollar has weakened on the back of downbeat US economic data out this week.
Major currencies strengthened against the dollar as figures showed a slowdown in both manufacturing growth and property sales.
US employment figures due out by the end of the week are also expected to further highlight strain in the economy, while some investors have expressed fears over a possible double dip recession.
Oil prices are usually boosted by weak performance in the dollar.
Speaking to the Financial Times, the head of oil research at Societe Generale in London, Michael Wittner, said the oil markets are concerned that a loss in momentum could be a sign of the development of a "more significant slowdown".
Barclays Capital said oil prices remain "under the wrath of macroeconomic pessimism" and that the market is "engulfed in a sentiment which is seeking out to be bearish".
