The FTSE 100 has fallen into the red, weighed down by a stronger pound as US president Donald Trump knocked the dollar with criticism of the Federal Reserve.
The UK blue-chip index fell 16 points to 7,575, as the pound climbed 0.5% against the dollar, trading at $1.286.
A stronger pound tends to hinder the FTSE 100, whose stocks rely on overseas markets for around three-quarters of their earnings.
The dollar sold off after Trump said in an interview with Reuters that he was 'not thrilled' with the Federal Reserve's raising of interest rates and said the central bank should be doing more to support him in his trade talks.
'We're negotiating very powerfully and strongly with other nations. We're going to win. But during that period of time I should be given some help from the Fed,' he said.
Fiona Cincotta, senior market analyst at City Index, said it was 'unlikely to be the last' criticism the Fed received from Trump.
'What is interesting is the amount of attention dollar traders have paid to the comments, despite Trump talking up the dollar in a tweet only a week ago,' she said.
That sent the dollar down 0.4% against a global basket of currencies, with the greenback 1.2% lower over the week.
Against the pound its losses were greater, as sterling gained support from data showing the UK government enjoying its biggest surplus in 18 years.
Shares in supermarkets meanwhile jumped after strong sales data from market researchers Kantar.