U.S. crude prices fell on Monday as rising domestic inventories kept weighing on the markets and investors worried about possible Greek debt default.

U.S. crude stocks have risen for recent three weeks, indicating weak demand in the world largest oil consumer, which heavily burdened the crude markets.

Meanwhile, risk aversion increased sharply after Greece failed to strike a deal to secure the 130 billion euro rescue fund before another deadline of Monday, pushing the EU country closer to a chaotic debt default. To add to the pressure, Greece could only be the first domino in the debt-burdened region. Portugal, for example, was also facing mounting obligations that it can't meet.

But in London, Brent crude managed to rise as cold weather in Europe and supplies disruption risks in the Middle East offset Greece concerns.

Light, sweet crude for March delivery declined 93 cents, or 0. 95 percent to settle at 96.91 dollars a barrel on the New York Mercantile Exchange. In London, Brent crude rose and last traded around 116 dollars a barrel.