The London market was left languishing in the red as stocks felt the weight of tumbling oil prices and fresh concern over global growth.

The FTSE 100 Index was 38.9 points lower at 6191.93, as two manufacturing surveys pointed to lacklustre activity in China, while the OECD warned that Brexit would have a ''substantial'' impact on the UK and global economy.

The private Caixin/Markit survey showed China's factory activity fell to 49.2 last month, down from 49.4 in April, while the official index by the Chinese Federation of Logistics & Purchasing was more optimistic at 50.1 for May. A reading above 50 indicates expansion.

Mining giant Rio Tinto was nearly 4% lower, while Antofagasta was down more than 3%, as investors feared lower manufacturing output in China could lead to a weaker demand for commodities and slower global growth.

Stocks were also under pressure after the Organisation for Economic Co-operation and Development (OECD) slashed its forecasts for the UK economy, as it said Brexit fears have already ''undermined'' growth.

It added that Brexit would have significant impact on growth across Europe and rest of the world and trigger turbulence in financial markets.

In Europe, Germany's Dax dropped 0.6% and the Cac 40 in France was down 0.8%.

Brent crude fell by more than a dollar at one stage, before easing back to a fall of 0.6% at 49.58 US dollars a barrel.

The oil price was tumbling ahead of a crunch meeting between members of the Opec cartel, with hopes for an agreement to cut production fading.

Sterling was 0.6% lower against the dollar at 1.439 as EU referendum polls show the leave camp is narrowing the gap on those campaigning to remain.

The pound was nearly 1% down against the euro at 1.288.

In stocks, Rio Tinto slipped 74.5p to 1868p, Antofagasta was 13.3p down at 415.7p and BP fell 3.7p to 353.6p.

Plumb Center owner Wolseley was the biggest faller on the top tier as it moved to ramp up restructuring efforts across the UK and Europe after revealing a sharp slowdown in sales growth.

The company said like-for-like revenue growth dropped to 1% in recent weeks, down from 2.8% in its third quarter.

Shares dropped more than 5%, or 223p, to 3828p.

Housing stocks were out of favour as figures revealed a slowdown in annual house price growth last month.

The average price of a UK house edged up 0.2% to £204,368 in May, but year-on-year growth slipped back to 4.7% from 4.9% in April, according to Nationwide Building Society.

Charles Church owner Persimmon fell 64p to 2038p, Taylor Wimpey was 7.7p lower at 197.7p, and Barratt Developments dropped 18.5p to 573.5p.

Sainsbury's plunged more than 4% as new data from Kantar Worldpanel pointed to falling sales and shrinking market share.

The supermarket saw sales drop 1.2% over the last quarter, driven by a decline in pack sales after the retailer shifted away from promotions to everyday price cuts, according to Kantar.

Shares were down 11.6p to 256.9p.

Away from the top tier, Halfords slumped despite profits nudging up as the retailer's turnaround continues under chief executive Jill McDonald.

The car parts to bicycles firm said full year pre-tax profit rose 0.5% to £81.5 million after sales at its retail and Autocentre arms saw growth.

Shares in the FTSE 250 company were more than 7% lower or 31.7p to 406.9p.

The biggest risers on the FTSE 100 Index were Shire up 120p to 4380p, Fresnillo up 23p to 1032p, Mediclinic International up 17p to 883.5p, Pearson up 9.5p to 848p.

The biggest fallers on the FTSE 100 Index were Wolseley down 223p to 3828p, Sainsbury's down 11.6p to 256.9p, Rio Tinto down 74.5p to 1868p, Taylor Wimpey down 7.7p to 197.7p.