The UK's blue-chip index fell on Friday as investors awaited news on whether the United States would impose new tariffs on Chinese imports while a data breach at British Airways triggered a fall in its owner's shares.
The FTSE 100 fell 0.6 percent at 7,277.70 points, accelerating losses in afternoon trading as the pound rose after EU negotiator Michel Barnier said the bloc was open to discussing other "backstops" on the Brexit issue.
"As it has done for much of the week, the pound came to dominate on Friday, punishing the FTSE in the process," said Connor Campbell, analyst for Spreadex.com.
Later in the session White House Economic Adviser Larry Kudlow told CNBC that the United States continued to talk with China about a number of trade issues but added that so far China has not met US requests.
The FTSE ended at a fresh five-month low, down more than 2 percent on the week.
Shares in British Airways' parent International Airlines Group fell 1.4 percent after the airline reported the theft of financial and personal data of potentially hundreds of thousands of customers.
Among mid-caps, British pub operator Greene King surged 7.5 percent after reporting a boost in sales thanks to exceptionally warm weather and the soccer World Cup.
The company, which owns ale brands such as Greene King IPA, Old Speckled Hen and Abbot Ale, said it sold 3.7 million pints of beer during England's seven World Cup matches.
Shares in Ashmore rose 1.4 percent after the emerging markets asset manager published full-year results. UK-focused oil company EnQuest fell more than 13 percent after announcing plans for a rights issue to finance acquisition of an oilfield from BP.
Online retail trading platform Plus500 lost 7.3 percent to 15.44 pounds after Playtech said it has sold its entire 10 percent shareholding for about 176 million pounds, equating to 15.50 pence per share.