Investor concern that US president Donald Trump could face impeachment over the James Comey affair and at the very least see his policy programme delayed weighed on markets this afternoon.
On Wall Street banks were among the main fallers, leading the S&P 500 1% lower to 2,377 while the Nadaq technology index shed 1.2% at 6,097 as controversy over Trump's decision to sack the former FBI director intensified.
Reports that Trump asked Comey to halt an investigation into his former national security adviser Michael Flynn raised the prospect that the president could be charged with obstruction of justice.
This saw the dollar fall against a basket of currencies with the pound stronger at $1.2974 and the euro up at $1.1140, The US currency has given up all its gains since the Trump's election in November.
In London the FTSE 100 retreated 25 points to 7,496 with property stocks weak after British Land (BLND) said it was cutting its amount of speculative building and warned of uncertainty in the market as Britain leaves the European Union.
Shares in British Land were one of the biggest fallers on the index, down 3.5% at 650p, as the real estate investment trust said it was reducing the amount of land it was developing before securing tenants.
'We have entered a prolonged period of uncertainty and businesses will face a number of headwinds,' the company said in its full-year results.
'Mindful of this background, but facing a clear need to move forward, occupiers are continuing to make decisions, but plans are taking longer to come to fruition.
'We expect Brexit-related headwinds to impact our occupational markets. In offices, it will be some years before we have clarity on the impact of proposed regulatory changes which may affect occupier demand, particularly in financial services.'
'British Land is clearly uncomfortable about the future,' said Nicholas Hyett, equity analyst at Hargreaves Lansdown. 'Speculative developments have been reined right back and leverage is falling as the group sells some high profile assets, including a 50% stake in the Cheesegrater. That's sensible given the group's disproportionate exposure to the prestige London office space most likely to be hit if Brexit results in a mass exodus of bankers, lawyers and the like.'
Lloyds (LLOY) gave up some of its earlier gains prompted by the government selling the last of its remaining stake in the bank to trade 1.3% up at 71p.
Among 'mid cap' stocks, Sophos (SOPH) initially soared 105p to 407.1p on strong results and a bright outlook but fell back in the afternoon to trade 6% higher at 390.6p. Shares in the cyber security firm are up 20% this week, after the WannaCry virus sparked demand for the sector.
Mitchells & Butlers (MAB) was the biggest faller, down 5.2% at 260p as the pub operator warned of 'fragile' consumer confidence.