Crude oil futures declined Tuesday amid concerns that Spain's banking bailout may not be enough to rescue the country from the financial crisis.

Light sweet crude for July delivery declined 0.73 percent, or 60 cents, to $82.10 a barrel in electronic trading on the New York Mercantile Exchange during European trading hours. Brent crude oil futures for July delivery fell 0.38 percent, or 37 cents, to $97.63 a barrel on the ICE futures exchange in London.

Earlier, light sweet crude declined to an 8-month low of $81.07 a barrel in Asian trade. Global markets and commodities failed to uphold the early rallies on the Spanish aid of 100 billion euros ($124.9 billion) on concerns that the bailout might not be enough to rescue the country from the financial crisis.

The group of finance ministers from the 17-nation single currency bloc agreed Saturday to lend Spain 100 billion euros to restructure its troubled banks. The figure was much higher than the International Monetary Fund's initial estimation of 40 billion euros.

The Spanish 10-year bond yields were above 6.5 percent Monday on concerns about the impact the bailout package would have on public debt. The aid could add up to 10 percentage points to Spain's debt ratio while many analysts believe that with the capital flowing out of Spain, the current aid is only a short-term fix, and the country will eventually need a full state bailout.

We will see this kind of volatility because of the uncertainty over Greek elections, lack of clarity on the length and breadth of the Spanish bank bailout. I am not surprised to see the pull back in oil prices, Ben Le Brun, a Sydney-based markets analyst at OptionsXpress, told Reuters.

Oil prices were also under pressure after Saudi Arabia called for an increase in OPEC's output target for the second half of the year despite a recent dip in crude prices. OPEC is almost certain to maintain its official output ceiling at 30 million barrels per day at its meeting Thursday.

Meanwhile, the United States exempted seven economies from financial sanction after these nations significantly reduced their volume of crude oil purchases from Iran.

Countries including India, Taiwan, South Korea, Turkey, South Africa, Malaysia and Sri Lanka will not be penalized and cut off from the U.S. financial system under sanctions imposed by the President Barack Obama last year.

By reducing Iran's oil sales, we are sending a decisive message to Iran's leaders: until they take concrete actions to satisfy the concerns of the international community, they will continue to face increasing isolation and pressure, U.S. Secretary of State Hillary Clinton said in a statement Monday.