Britain's FTSE halts five-day winning streak
* FTSE 100 edges lower after 5-day winning run
* Ex-dividends take around 11 points off the index
* Glencore up after announcing share buyback
* Fall in China iron ore prices hits mining sector
LONDON, Aug 20 (Reuters) - British shares fell on Wednesday, halting a five-day winning run as a fall in major mining shares pushed the FTSE index off a three-week high.
The blue-chip FTSE 100 index was down by 0.3 percent, or 17.54 points, at 6,761.77 points in early trade.
The FTSE 350 Mining Index slipped 0.1 percent, as a fall in the prices of iron ore and steel in China - the world's biggest metals consumer - pegged back mining stocks.
However, mining and commodities group Glencore outperformed to rise 0.5 percent after the company announced a share buyback programme of up to $1 billion as it posted a forecast-beating 8 percent rise in first-half core profit.
Banking group Standard Chartered also outperformed with a 0.7 percent advance.
Standard Chartered said late on Tuesday, after European stock markets had closed, that it would pay a $300 million penalty and suspend or exit some important businesses after failing to weed out risky transactions that could be linked to money laundering.
Traders said the gains in the bank's share price reflected an element of relief that the penalty was now out of the way, after media reports about it had circulated beforehand. Standard Chartered's underlying business remained in good shape, they said.
"They've got more than enough capital to cover the fine," said Beaufort Securities sales trader Basil Petrides.
The effect of several major companies, including bank HSBC and British American Tobacco, going "ex-dividend" - namely having their shares trade without the attraction of their latest dividend - also took some 11 points off the FTSE 100 index.
The index hit a peak of 6,894.88 points in mid-May, which marked its highest level since December 1999, but has since given up much of that ground.
Hantec Markets analyst Richard Perry said he would look to see if the FTSE could get back up to the 6,834 point level, which would indicate the market's recent rebound had more strength left in it.
"If the FTSE falls over again around these levels, it would just perpetuate the drift lower that we've seen in the last two months," he said. (Editing by Susan Fenton)