emirates7 - Oil prices tumbled 4 percent on Monday, with Brent crude futures falling $3.96, or 4.1 percent, to $92.82 by 0329 ​GMT after briefly slipping under the key support level of $90 earlier in the session.

US West ​Texas Intermediate crude was at $85.29 a barrel, down $4.02, or 4.5 percent.

Both contracts are trading at their lowest levels in nearly a week after rising for the past three weeks.