Britain's FTSE underperforms, mining shares a drag

* FTSE 100 down 0.2 pct, underperforms Europe

* FTSE 350 mining index down almost 2 pct

* Intertek shares up after results

* Rolls-Royce extends gains on investor stake

* Financial tech company Fidessa slumps (Updates prices.)

By Lionel Laurent

LONDON, Aug 3 (Reuters) - Top UK shares underperformed their European counterparts on Monday, with mining stocks hit when weaker-than-expected manufacturing in China caused global commodity prices to tumble.

Data showing UK manufacturing growth picked up in July but new orders grew at the slowest pace in nearly a year did little to change share prices.

The FTSE 100, which is more skewed towards energy and natural resources than many indexes in Europe, was down 0.2 percent at 1413 GMT. The pan-European FTSEurofirst 300 was up 0.6 percent, but the FTSE 350 mining index was down over 3 percent.

UK stocks have underperformed Europe by some 14 percentage points so far this year. Credit Suisse (NYSE: CS - news) downgraded UK stocks last week, citing the risk of an interest-rate increase as well as the commodities sell-off.

"It has been quite relentless for mining stocks ... the London market is quite heavy on commodities stocks and that is not helping things," said Mark Ward, head of execution at Sanlam Securities.

But shares in testing firm Intertek Group (Other OTC: IKTSF - news) jumped more than 10 percent after it posted an improvement in first-half organic growth and maintained its full-year guidance.

HSBC beat expectations with a 10 percent rise in first-half profits and an agreement to sell Banco Bradesco for over $5 billion. Its shares rose 0.2 percent.

Rolls Royce (LSE: RR.L - news) rose more than 4 percent, extending gains from Friday after an announcement that U.S. activist investor ValueAct had taken a 5.4 percent stake.

Financial-technology company Fidessa fell 12 percent, however, after warning of greater "headwinds" into 2016 as competition among its financial-sector customers might lead to further closures or mergers. (Reporting by Lionel Laurent, editing by Larry King)