The London market has ended the week lower after light trading in the US and steep overnight falls in China following the announcement of a probe into two major brokers.

Chinese authorities said they will investigate the short-selling practices of two major brokerages for their roles in this summer's market plunge, which rocked the world's second largest economy.

The FTSE 100 Index closed down 18 points at 6375.2, after the Shanghai Composite Index fell 5.5 per cent overnight.

The Footsie more than surrendered the 55-point gain made in the previous session, retreating from the psychologically important 6400 mark.

Germany's DAX and the Cac 40 in France were both marginally lower. In New York the Dow Jones Industrial Average was also slightly down, following thin trading surrounding the Thanksgiving holidays.

The pound fell a cent against the US dollar to just over 1.50, after revised official data showed that UK economic growth remained at 0.5 per cent in the third quarter, dipping from 0.7 per cent in the previous quarter. Sterling was also slightly down against the euro at 1.42.

Miners were the biggest fallers with Anglo American down 35.7p to 400.2p, Rio Tinto 72p lower to 2199p and BHP Billiton fell 25.6p to 807.6p.

Heavyweight oil firms also contributed to the slide with BP slipping 3.1p to 386.6p, while Royal Dutch Shell was 19p lower to 1673.5p.

Engineering firm Rolls-Royce lifted 5p to 606.5p, as traders warmed to the firm's turnaround plan outlined earlier this week to cut costs by between £150 million and £200m a year.

Chief executive Warren East said management roles will be cut - on top of the 3,600 redundancies previously announced over the next 18 months.

But he ruled out selling off large parts of the business wholesale. The stock has fallen by almost a third since the start of the year.

Black Friday sales fever saw Dixons Carphone lift 7.8p to 481.6p, as the firm has been outpacing rival electrical retailers.

The firm recently hailed a ''very encouraging'' start to its trading year as revenues surged on the back of strong smartphone and TV sales.

Other retailers rose in a day that is forecast to generate £1 billion of sales. Next was 50p higher to 7920p, while Sports Direct International was up 3p to 711.5p.

Elsewhere, the owner of South West Water Pennon Group said pre-tax profits climbed 6.8 per cent to £106.8 million in the six months to the end of September compared to a year ago, after strong earnings from its recycling plants.

Its South West Water arm supplies water to 1.7 million households in Devon, Cornwall and parts of Somerset and Dorset, and the group also owns Bournemouth Water. Shares lifted 46p to 883p.

The biggest risers in the FTSE 100 Index were Inmarsat up 25p at 1113p, Severn Trent up 46p at 2248p, Dixons Carphone up 7.8p at 481.6p, and United Utilities up 12.5p at 978.5p.

The biggest fallers in the FTSE 100 Index were Anglo American down 35.7p at 400.2p, Fresnillo down 34p at 715p, Randgold Resources down 179p at 3997p and Glencore down 4p at 91.9p.