U.S.-China trade concerns weigh on FTSE 100

By Muvija M and Yadarisa Shabong

(Reuters) - Britain's main stock index tumbled to a near six-week low on Tuesday as investors returned from a long weekend to a threat of more U.S. tariffs on China that triggered a selloff led by oil majors and banks.

The FTSE 100 slumped 1.6 percent, while midcaps were 1.2 percent lower.

HSBC and Prudential fell as U.S. President Donald Trump's threat to impose additional tariffs on Chinese goods hit Asia-exposed financial stocks.

Oil majors Shell and BP suffered their worst day since early December as the trade nerves fanned concerns about global growth and demand.

Industrial groups Melrose and Ashtead lost 5.8 percent and 3.5 percent respectively.

"There is a sense that the U.S. is working extremely hard to extract last-minute concessions from China ahead of a planned visit by Vice-Premier Liu He," Neil Wilson, an analyst at Markets.com, said.

All but one blue-chip sector ended in the red as investors steered away from riskier assets and moved to defensive stocks, viewed as better bets in times of economic uncertainty.

That benefited Utilities SSE and Centrica, and pharmaceutical groups Hikma and AstraZeneca were also higher.

Volumes were high after markets were shut for a holiday on Monday. The FTSE 100's volume was 130 percent of its daily average, and the FTSE 250's stood at 110 percent.

A further blow to equities was the European Commission cutting its quarterly growth forecast for the euro zone.

"The timing of the EU’s announcement isn't great, but global trade tensions are likely to hurt the region," said CMC Markets analyst David Madden.

The more domestically-focused midcaps were also weighed down by a weaker pound, which dipped on rising concerns about the progress of Brexit negotiations and worries UK Prime Minister Theresa May is facing a mounting challenge to her leadership.

Security group G4S gave up nearly 3 percent after Garda World said on Sunday it would not make an offer for the company, while Essentra skidded 4.8 percent after a rating downgrade by Stifel.

Domino's Pizza, Britain's biggest pizza delivery firm, dipped 1.5 percent as the company said it no longer expected its international business to break even this year. It earlier fell as much as 12 percent.

AIM-listed Purplebricks tanked 11.9 percent after the online estate agent said its founder and chief executive, Michael Bruce, would quit immediately as the company winds down its Australian operations and reviews its U.S. business.

(Reporting by Muvija M in Bengaluru, editing by Dale Hudson and John Stonestreet)