Blue-chip shares have drifted lower as disappointing US economic data blunted earlier enthusiasm over the Chinese economy.

Far weaker-than-expected manufacturing figures from America saw the FTSE 100 Index slip 25.7 points to 6597.4, although the Dow Jones Industrial Average on Wall Street shook off the downbeat data to nudge higher in early trading.

Trading had starting on the front foot in London after reports that Chinese premier Li Keqiang said growth must be kept above 7% reassured traders, suggesting Beijing will take measures to support the world's second-biggest economy, following a recent slip in its pace of expansion.

Two straight quarters of slowing growth in China have shaken global markets in recent months and also hurt commodity prices on fears of falling demand.

Alpari analyst Craig Erlam said the comments showed while China remained committed to transforming itself into a more consumer-led economy it would continue to support growth amid fears it could fall below 7% without fiscal stimulus. Rising sentiment about Chinese demand saw miners dominate the leaderboard on the London market, with Glencore Xstrata surging 13.7p to 282.7p and Rio Tinto add 97.5p to 3000p.

Hopes that UK growth figures later this week will signal a sustained recovery saw the pound trade close to recent four-week highs against the US dollar, at $1.54.

Sterling also largely held firm against the euro, at €1.16.

In corporate news, loss-making Premier Foods – home to Mr Kipling and Bisto – received a boost as the company said it was on track for a better than expected year.

Cost savings and a sixth consecutive quarter of growth for its frontline brands, which also include Ambrosia and Batchelors, meant losses for the six months to June 30 were pared by around half to £23.5 million. Shares were up 5.25p or 6% to 90.25p.

Meanwhile, Imperial Leather soap maker PZ Cussons reported a 16.5% rise in underlying profits, raised its dividend payment and said performance had been in line with expectations thanks to new product launches such as its Mum & Me range.

Shares were up 8.5p to 396.5p as it also revealed more cost cuts, including the closure of three loss-making Sanctuary spas.

But budget airline easyJet was among the heaviest fallers in the top tier after the recent heatwave prompted HSBC to downgrade its target price and profits forecast based on fewer people booking last-minute holidays due to the hot weather. Its shares were 51p lower to 1336p.

Blue chip industrial group Croda International – which makes natural chemicals for cosmetics groups including L'Oreal and Estee Lauder – also slumped after second-quarter profits missed expectations.