Commodities boost Britain's FTSE to another weekly rise

* FTSE 100 up 0.7 pct

* Miners, energy rally with commodities

* FTSE has outperformed Europe in recent weeks

* Marks and Spencer extends gains

* Experian (Other OTC: EXPGF - news) falls after double downgrade on Brazil risk (Adds detail and quote, updates prices)

By Kit Rees and Alistair Smout

LONDON, April 8 (Reuters) - Britain's top share index was on track for another weekly rise on Friday, helped by buoyant commodity stocks and continuing a run which has seen it outperform its European peers.

The FTSE 100 was up 42.54 points or 0.7 percent at 6,179.43 by 1122 GMT, up 0.5 percent for the week.

Energy shares contributed over 11 points to gains, with BP and Shell (LSE: RDSB.L - news) adding the most points to the index after Brent crude broke back above $40 dollars a barrel.

Mining shares also rose 1.1 percent, with the likes of Rio Tinto (LSE: RIO.L - news) , BHP Billiton (NYSE: BBL - news) , Antofagasta (LSE: ANTO.L - news) , Glencore (Xetra: A1JAGV - news) and Anglo American (LSE: AAL.L - news) up between 0.9 to 1.5 percent, although the price of copper declined slightly.

Despite the moves higher, some analysts weren't convinced that investors' appetite for risk had increased.

"I think there is definitely an element of short-covering to some of the upside moves that we're seeing at the moment, and it isn't necessarily manifesting (in) any real risk-on sentiment," Brenda Kelly, head analyst at London Capital Group, said.

Retailer Marks and Spencer also gained, extending its rally from the previous session when its results beat expectations.

It (Other OTC: ITGL - news) gained 2.4 percent after Canaccord Genuity (Other OTC: CCORF - news) upgraded its rating on the stock to "buy" from "speculative buy", which put Marks and Spencer's total gains for the week at 8.8 percent.

The FTSE 100's heavy weighting in commodity sectors has helped it to outperform other European stocks in recent weeks.

The FTSE 100 was set for its third weekly rise in the last four weeks. In the same time, the pan-European FTSEurofirst 300 has posted four straight weeks of losses.

Experian was down 1.6 percent, the biggest faller after the credit data company was received a double downgrade from HSBC, being cut to "reduce" from "buy", citing structural risks in Brazil

"Brazil's largest commercial banks ... are working to set up a Positive credit bureau that will compete with Experian," analysts at HSBC said in a note, adding that this could hit Experian's valuation.

"We believe such a market development poses a multiple de-rating threat," they said.

Likewise asset manager Schroders (LSE: SDR.L - news) dropped 1 percent after Exane BNP Paribas cut its rating on the stock to "neutral", citing the company's weak flow and fund performance momentum.

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If you have any thoughts, suggestions or feedback on this, please email mike.dolan@thomsonreuters.com.

Mike Dolan, Markets Editor EMEA. (Editing by Hugh Lawson)