The blue-chip FTSE 100 index ended the session 3.5% lower and was down 6.4% over the week, with precious metal miners, automakers and travel stocks were the main losing sub-indexes.
Russian forces in Ukraine seized Europe's biggest nuclear power plant on Friday in what the U.S. said was a reckless assault, although a blaze in a training building was put out and officials said the facility was now safe.
Banking shares including HSBC and Barclays and oil and gas giants Shell and BP were among the top drags on the FTSE 100 on Friday.
"People are nervous around the Ukraine headlines and nobody wants to own stocks. It's Friday and nobody knows what will happen over the weekend, which adds to the risk averseness," said Keith Temperton, a sales trader at Forte Securities.
The FTSE 100 has erased all gains made this year to trade 5.1% lower as soaring commodity prices after Russia's invasion of Ukraine have stoked global inflation and growth worries.
"It is becoming difficult to remain constructive on risk in the face of the current exceptional uncertainty," Andrea Cicione, head of strategy at TS Lombard, said.
British firms including Marks & Spencer, recruiter Hays, supermarket group Sainsbury's and the world's largest advertising firm WPP have suspended their Russian operations.
The domestically focussed mid-cap index fell 3.5% on Friday and is down 7% in its worst week since March 2020.
Among other stocks, Hammerson gained 1.1% after the mall operator reported a smaller annual loss and a drop in debt levels.
Mitie's shares sank 10.6% after Britain's antitrust regulator said it is investigating the outsourcing firm over potential breaches of competition law relating to the tender for contracts to run two immigration removal centres.
(Reporting by Amal S in Bengaluru; Editing by Saikat Chatterjee, Aditya Soni and Alexander Smith)
By Amal S and Shashank Nayar
