Steep losses in energy stocks held back gains in London's blue-chip index on Monday, as oil prices slumped on concerns over rising COVID-19 cases, while financial services group Hargreaves Lansdown plummeted on weak earnings.

Britain's biggest fund supermarket Hargreaves Lansdown tumbled 11.3% and was the biggest faller in the FTSE 100 after it missed profit estimates, even though it attracted record numbers of new clients on the back of rising retail participation.

The FTSE 100 index ended 0.1% higher on gains in defensive sectors, including consumer staples and healthcare, while mining stocks recovered from early losses.

Stock markets lower as virus fears hit oil prices

Energy companies weighed the most on the index, with Royal Dutch Shell and BP falling 0.8% and 0.7%, respectively.

Oil prices slumped around 4% as rising COVID-19 cases, particularly in China, prompted concerns over new curbs on activity, which could hurt demand for oil.

"The drop seems to be a short-term blip rather than a market-wide worry as support for commodities still seems to be unshaken," said David Madden, an analyst at Equiti Capital.

The mid-cap index ended flat. Global recruiter PageGroup was among the worst performers in the index, falling 3.2% after its first-half profit fell below 2019 levels.

The FTSE 100 index has gained nearly 10% so far this year but has largely lagged US and European peers, hurt by a resurgence in COVID-19 infections and inflation fears outweighing optimism around robust corporate earnings.

FTSE 100 gains on robust earnings, bumper dividends

As the UK economy re-opens, the market knows higher inflation will not be an issue as long as it is in tandem with economic growth, Madden said.

Among other stocks, Vecture gained 5.5% after tobacco company Philip Morris raised its bid for the drugmaker to 165 pence ($2.29) per share.

Deliveroo surged 4.5% after its German rival Delivery Hero took a 5.09% stake in the British food delivery company.