Brent crude oil sharply fell 1.7% to $63.28 per barrel before easing back on record US production and rising inventories, weighing on oil majors BP (BP.) and Royal Dutch Shell (RDSB).
Shell slid 1.7% to £22.79 and BP retreated 1.1% to 469.7p.
The FTSE 100 was resilient despite the oil majors being among the largest in terms of market cap on the index, which closed 0.3% higher at 7,234.
US equities remained steady on Thursday with the S&P 500 advancing 0.2% to 2,705 around 4:45pm UK time.
MID AND LARGE CAP RISERS AND FALLERS
Shares in Indivior (INDV) slumped 7.4% after falling from an operating profit to a loss of $115m in the fourth quarter of 2017 due to pre-launch costs for its SUBLOCADE and RBP-7000 products.
ConvaTec (CTEC) beat lower full year sales expectations, helping to overshadow ongoing supply issues and pushing its shares 7.3% higher to 212.2p.
Engineer GKN (GKN) urged shareholders to resist the hostile takeover by Melrose (MRO), arguing the attempt is opportunistic.
RELX (REL) was flat at £14.66 despite solid 2017 results. The company also announced it was ditching its dual share structure for a single PLC share listed in Amsterdam and London.
Insurer Lancashire (LRE) revealed 2018 will be another challenging year after falling into the red. Pre-tax losses hit £72.9m in the year to 31 December, down from a pre-tax profit of £150.4m in 2016. The stock declined 8.9% to 595.5p.
SMALL CAP RISERS AND FALLERS
Oxford BioMedica (OXB) announced a new collaboration for its haemophilia treatments with Bioverativ, helping the shares rally 11.7% to 12p.
On AIM, electronics engineer Stadium (SDM) recommended a £45.8m takeover from TT Electronics (TTG), prompting the shares to soar 43.2% to 119.6p.