Commodities help FTSE seal eight-week winning streak

* FTSE 100 down 0.1 pct

* Index hit record close on Thursday

* AstraZeneca (NYSE: AZN - news) falls after results

* Glencore (Frankfurt: 8GC.F - news) drops after report of UK bribery probe (Adds detail, updates prices at close)

By Helen Reid and Kit Rees

LONDON, May 18 (Reuters) - Britain's leading stock index posted its eighth straight week of gains despite dipping slightly on Friday as investor enthusiasm waned following the previous day's record close.

The FTSE 100 ended the session down 0.1 percent at 7,778.79 points, in line with the FTSE 250 which hit a fresh record earlier in the session before turning lower.

The FTSE sealed its longest winning streak in 13 years, marking a strong comeback for British stocks.

Commodities, a key part of the UK stock market, have driven much of the recent climb in the FTSE 100, which has also benefited from a string of brokers recommending investors buy back into the region. The index made a full recovery from its February losses.

On Friday, weak results from AstraZeneca sent the shares down nearly 2 percent, weighing on the healthcare sector - a big drag on the overall index.

The drugmaker's first-quarter profit was hit by generic competition to cholesterol drug Crestor, and higher costs.

"Base business continues to decline faster than expectations, resulting in a miss both on product sales and core EPS," said Goldman Sachs (NYSE: GS-PB - news) analysts.

Oil stocks were mixed on Friday, however, having surged all week thanks to crude prices which breached the $80/barrel barrier on Thursday after a strong run.

Major Royal Dutch Shell fell 0.5 percent, while BP edged 0.4 percent higher.

Yet the biggest faller in the commodity space was miner Glencore, down 4.4 percent at the bottom of the FTSE following a report by Bloomberg that it may face an enquiry from Britain's Serious Fraud Office into allegations of bribery linked to its operations in Democratic Republic of Congo.

Glencore said it could not comment on the report.

Shares (Berlin: DI6.BE - news) in battery maker Johnson Matthey (LSE: JMAT.L - news) fell 1.8 percent after a note from UBS (LSE: 0QNR.L - news) listing "three reasons to sell" the stock.

Analysts at the Swiss bank said the company's board would likely need to raise capital expenditure expectations in order to cement its credibility as a supplier to global automakers.

"Competitor Umicore has significantly expanded its ambitions in battery materials during 2018," they added, noting the Belgian chemicals company is targeting larger volumes of cathode production.

Among smaller stocks, Carpetright (Other OTC: CGHXF - news) shares jumped more than 11 percent after the struggling retailer said it would raise around 60 million pounds through a share issue.

(Reporting by Helen Reid and Kit Rees Editing by Andrew Heavens)