Britain's FTSE falls, Glencore the worst performer

* FTSE 100 down 1.1 pct

* Glencore (Xetra: A1JAGV - news) drops 5.5 pct

* Admiral jumps on forecast-beating results

By Liisa Tuhkanen

LONDON, Aug 19 (Reuters) - Britain's top share index fell on Wednesday, in line with other European equities, dragged lower by commodity stocks and by growing anxiety over China's economy.

The blue-chip FTSE 100 index was down 1.1 percent at 6,453.72 points by 0826 GMT. It (Other OTC: ITGL - news) closed 0.4 percent lower on Tuesday, more than 8 percent below a record high of 7,122.74 points hit in April.

China's stock markets tumbled and soared on Wednesday despite government efforts to stabilise them, although they ended higher after the central bank injected more funds into the financial system for the second day in a row.

Fears over the state of China's economy, the second-largest in the world, have come to eclipse those over Greece's debt problems in recent weeks, with China's devaluation of its yuan currency on Aug. 11 adding to concerns.

"The general sentiment is fairly skittish at the moment, and the outlook for China certainly hasn't helped," said Richard Hunter, head of equities at Hargreaves Lansdown (LSE: HL.L - news) .

"The FTSE 100 is actually in negative territory for the year as we speak, and it's quite difficult to see from here what sort of short-term positive impetus the market might take."

The index has declined 1.8 percent since the start of the year.

The pan-European FTSEurofirst 300 index fell 1.2 percent, also driven lower by worries over China.

In London, miner and commodities trader Glencore declined the most, down 5.5 percent, after it posted a 29 percent fall in first-half earnings due to the slide in metal and oil prices and said capital spending next year was expected to be lower than this year.

Other blue-chip miners also fell due to weaker metals prices because of fears that demand from China -- the world's largest metals consumer -- will take a hit.

Anglo American (LSE: AAL.L - news) , BHP Billiton (NYSE: BBL - news) and Rio Tinto (LSE: RIO.L - news) fell between 1.8 and 1.3 percent, while the FT350 Mining index dropped 1.9 percent.

"Oil and mining stocks added together broadly account for 25 to 30 percent of the index by capitalisation, so clearly that also weighs and has weighed on the index," Hunter said.

Leading the few blue-chip gainers, British insurer Admiral jumped 4.7 percent after posting a forecast-beating 1 percent rise in first-half pre-tax profits, helped by growing customer numbers and lower than expected claims.

Among small caps, North Sea-focused oil producer Enquest (LSE: ENQ.L - news) 's shares tumbled 6 percent after it reported a 34 percent decline in profit before tax and net costs for the first half of the financial year.

(Reporting by Liisa Tuhkanen; Editing by Raissa Kasolowsky)