Crude oil futures are slightly lower Thursday as investors await the outcome of the OPEC ministerial meeting in Vienna.

Light sweet crude for July delivery declined 0.11 percent or 9 cents to $82.53 a barrel in electronic trading on the New York Mercantile Exchange during European trading hours. Brent crude oil futures for July delivery fell 0.35 percent or 34 cents to $96.79 a barrel on the ICE futures exchange in London.

Leaders of the world's 12-member crude oil cartel are scheduled to meet in Vienna later Thursday to discuss production quotas. There are considerable differences among the group members with countries like Iran and Venezuela arguing in favor of cuts in the production quota after recent plunge in oil prices.

Oil prices have plunged more than 23 percent in the last one month, following concerns over the deepening euro zone sovereign debt crisis and waning global oil demand. However, Saudi Arabia will want to keep the market well-supplied ahead of the implementation of the tougher Western sanctions against Iran at the beginning of July.

We don't anticipate a change in OPEC quotas at the Vienna meeting as we still expect the Saudis to go their own way in maintaining output at a high enough level to meet needs of all buyers, Jim Ritterbusch, president of trading consultancy Ritterbusch & Associates in Galena, told Reuters.

On Wednesday, light sweet crude for July delivery declined 70 cents and settled at nearly 8-month low of $82.62 a barrel on the New York Mercantile Exchange as weaker-than-expected U.S. economic data and renewed concerns about euro zone weighed on the sentiment.

Investors' sentiment was dampened following weak economic data from the U.S. as the retail sales fell 0.2 percent in May and April. It was the first back-to-back decline in nearly two years and fueled the concern that the recovery in the world's largest economy is slackening.

Meanwhile, worries over the European debt crisis revived Wednesday after Moody's slashed Spain's credit rating by three notches to Baa3 from A3, citing the nation's increased debt burden due to the recently approved EU aid for Spanish banks.