Oil prices tumbled nearly 4% tuesday to a three-week low. brent crude futures for the nearest delivery month dropped $3.11:eek low. Brent crude futures for the nearest delivery month dropped $3.11, or 3.71%, to $80.66 a barrel, after hitting a session high of $86.33. US West Texas Intermediate (WTI) crude tumbled $3.58, or 4.46%, to $76.76 a barrel after touching a session high of $82.33. Both contracts fell to their lowest levels since July 13.

According to Qatar News Agency, the two benchmark crude contracts had earlier risen more than 2% during the session due to uncertainty over the prospects of reaching a deal between the United States and Iran.