Oil prices surged past $100 a barrel on Thursday as Iran-backed Houthi rebels targeted Red Sea shipping as threats by US President Donald Trump to strike them in return sent equity markets slumping.

The international benchmark Brent North Sea oil contract soared seven percent to over the symbolic $100 a barrel level, as the attacks potentially opened a new front in the Middle East war and Trump threatened the Houthis with "major military punishment."

Iran, meanwhile, vowed to continue striking the Gulf region so long as it remains under attack from US strikes.

While soaring oil prices generated the most attention, Wall Street stocks endured a downcast session after markets panned earnings reports by Google parent Alphabet and Tesla.

Alphabet finished down 6.9 percent while Tesla sank 14.5 percent as both companies came under scrutiny for massive capital spending drives.