The FTSE 100 dropped 0.49% or 28.19 points to 5,768.68 in early morning trading, as fears of lower demand from China dragged down mining stocks.
London's leading index of shares added to yesterday's triple-digit gains in early trading on Friday, before dipping into negative territory.
Positive earnings reports from some of the FTSE 100 top players have boosted the index this morning.
The FTSE advanced in early trading on Thursday following two days of losses as Shell posted bumper Q3 profits.
The FTSE is down over a percentage point in afternoon trading with better-than-expected growth figures failing to lift investors as concerns over the banking sector weigh on sentiment.
The FTSE 100 rose 0.9% to 5,791.10 in early morning trading as a weaker US dollar provided support for mining stocks.
The FTSE 100 remains marginally in the red this afternoon, with miners dragging on the index.
The FTSE 100 had a slow start to the week, down 0.32% or 18.43 points to 5,684.94, following mixed sessions in Asia and the US.
The index of 100 leading shares has closed down on the day, with major insurers the biggest drag on markets.
The FTSE opened at 5,727 this morning, sliding 0.08% in early trading, although there was a raft of M&A activity among the UK's largest companies.