The FTSE 100 fell almost 1% this afternoon, reversing early morning gains, due to rising political uncertainty in Ireland.
European stock markets fell this afternoon as China raised its bank reserve rate for the second time in a week in a bid to control inflation.
The FTSE ignored large gains on Wall Street overnight, falling 0.35% to 5,748.45 in early trading.
The FTSE took its early lead from strong gains in Asia rather than muted US markets, up by 0.5% to 5,723.51.
The FTSE 100 was down almost 2% this afternoon as fears over Europe's sovereign debt woes and tighter monetary policy in China continued to weigh on investors.
London's FTSE opened 1.7% down this morning on a poor day for global stocks, following heavy losses in Asia and fresh fears for the Irish economy.
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 100 opened positively in a week set to be dominated by a slew of US economic and political news.
Germany has agreed to give the EU's €440bn (£383bn) bail-out fund permanent status rather than letting it expire in 2013 as planned.