Crude prices slipped on Monday as concerns over the European economic outlook returned to markets amid worse-than-expected PMI data.

Crude prices were heavily pressured by the news that government debts of the European Union had risen despite harsh austerity plans. Besides, the euro zone's Purchase Manager's Index for Manufacturing and services sectors unexpectedly fell in April, dipping to a five-month low.

Politics caused more uncertainties to the European economy as a French opposition candidate edged out President Nicolas Sarkozy and the Dutch cabinet offered its resignation in a crisis over an austerity package.

The HSBC's preliminary reading for the purchasing managers index for China rose in April, but still remained below 50, indicating a contraction in industrial activities.

But there were still uncertainties about talks over the Iranian nuclear issue, which put a floor under crude prices. Although Iran was optimistic about the second round of talks scheduled in May, tensions and sanctions against Iran's oil industry could stay. And in Sudan, a key oil field was damaged by the clashes between the Sudan and South Sudan, which caused oil supplies to decrease.

Light, sweet crude for June delivery fell 77 cents, or 0.74 percent, to settle at 103.11 dollars a barrel on the New York Mercantile Exchange. In London, Brent crude for June delivery also declined slightly and last traded above 118 dollars a barrel.