Shares in FTSE 100 heavyweights Shell PLC (LSE:SHEL, NYSE:SHEL) and BP PLC (LSE:BP.) slipped on Friday as oil prices headed towards their largest weekly decline in almost a year.
At US$72.65 a barrel on Friday morning, Brent crude had fallen more than 8% over the week, while West Texas Intermediate was down 9% at US$69.17.
This was despite news the OPEC+ cartel would delay a planned increase in production from October to December.
Fears over a supply surplus into next year have emerged recently, with the fall also coming despite data from the US showing crude inventories had dropped to their lowest level in roughly a year last week.
Easing political tensions in Libya, which had seen exports slashed, prompted prices to fall heavily earlier in the week.
Shell fell 1.4% on Friday, while BP dipped 0.9%.