The main index was down 0.6%, while the FTSE 250, which hit a three-week high on Thursday after two Bank of England policymakers unexpectedly voted for lower interest rates, shed 0.5%.
Positive trade signals this week, including a report that an agreement between China and the United States to roll back tariffs as part of a "phase one" trade deal was all but done, had spurred a fresh round of bets on shares.
Some of that optimism faded after sources familiar with the talks said the plan faced opposition on multiple fronts and President Donald Trump said he had not agreed to rollbacks of U.S. tariffs sought by China.
Miners <.FTNMX1770> tumbled 2% on their worst day in a month, while Asia-focused financials Prudential and HSBC were also among big drags on the main bourse.
While off the week's highs, the FTSE still recorded gains of nearly 1% for the five days.
A near 20% surge for Warhammer-owner Games Workshop following upbeat forecasts helped cap losses on the midcap index, which marked its best week in four.
However, in a sign that worries over Brexit had far from receded, data from Halifax showed British house prices rose at their slowest annual pace in 6-1/2 years last month which led housebuilders lower.
Blue-chips Barratt and Berkeley dipped 2.2% and 1%, respectively.
Lloyd's insurer Beazley advanced 7% after it said year-to-date returns on investment had surged as falling U.S. yields boosted gains in its fixed income portfolio.
That followed a dive in shares of bigger rival Hiscox on Thursday, the latest sign of concerns over a jump in catastrophe claims due to hurricanes and other natural disasters.
"In the context of widespread concerns about U.S. casualty, the reminder that Beazley began opening their loss estimates at a higher level in 2018 is reassuring," Jefferies analysts wrote.
By Shashwat Awasthi and Muvija M