US drilling company Baker Hughes said the number of rigs drilling for crude in the US rose for a 14th consecutive week.
Drillers added five rigs in the week to April 21, bringing the total count to 688 – the most since April 2015 – as the US shale industry ramps up production.
The data only added to bearish sentiment as oil was set for the biggest weekly drop in a month.
Prices lurched another leg lower on Friday with market confidence in Opec’s ability to overpower a resurgent US shale industry wavering.
US marker West Texas Intermediate fell below $50 a barrel — down $1.39 to $49.32 — by 6.15pm in London. It is set for a drop of more than 7 per cent this week.
The global Brent benchmark dropped $1.34 to $51.66 a barrel, marking a 7.5 per cent drop for the week.