The blue chip FTSE 100 <.FTSE> index ended the session 1.1 percent lower at 7,309.96, its worst week since March.
Drops among cyclical sectors weighed on the index, with heavyweight miners Rio Tinto (>> Rio Tinto), BHP Billiton (>> BHP Billiton Plc), Anglo American (>> Anglo American) and Glencore (>> Glencore) all dropping between 2.9 to 3.1 percent, among the biggest fallers on the index as tensions between the U.S. and North Korea hit riskier assets, including metals prices [MET/L]
The broader UK mining sector <.FTNMX1770> fell 2.7 percent.
Friday was the FTSE's third straight day of losses, after U.S. President Donald Trump said that his earlier remark to unleash "fire and fury" on Pyongyang if it fired missiles to land near Guam, a U.S.-held Pacific island, may not have been tough enough.
"We've had such a period of low volatility in the markets, coupled that with high valuation, it only takes a bit of a wobble to cause a reaction like we've seen," Jonathan Roy, advisory investment manager at Charles Hanover Investments, said, adding that the reaction was still quite tepid by historical standards.
"The miners have been quite resilient over the first few days of the sell-off, they held up relatively well, but today especially you're starting to see that fall-out in mining stocks, so I think that brings in the question of Chinese demand," Roy added.
Among the early risers, soft drinks bottler Coca Cola HBC (>> Coca Cola HBC AG) jumped as much as 2.5 percent and touched a fresh record high after several brokers upped their price targets for the stock, following a strong set of results in the previous session which saw the firm's shares soar more than 9 percent.
Coca Cola HBC shares gave up those early gains to end the session flat, however.
"The business is in a sweet-spot, delivering volume improvement, strong price/mix and operating leverage," analysts at Credit Suisse said in a note.
"We take comfort that many of the smaller markets are growing strongly, offsetting declines in the key markets Italy, Russia (weather impact) and Nigeria (price increases)," they added.
UK mid cap stocks <.FTMC> also came under pressure, falling 0.8 percent as shares in Dixons Carphone (>> Dixons Carphone) slumped more than 7 percent to its lowest level since the aftermath of the Brexit vote last June, driven down by a double downgrade from a star broker.
(Reporting by Kit Rees; editing by Alister Doyle)
By Kit Rees