By Atul Prakash and Kit Rees
Britain's top share index fell as energy stocks came under pressure again from dropping oil prices, although the index recorded its best weekly performance since October following strong gains in the previous sessions.
The benchmark FTSE 100 index finished 0.4 percent weaker on Friday at 5,950.23 points after hitting a two-week high in the previous session. It gained more than four percent this week.
Investors traded cautiously ahead of the outcome of a EU summit to negotiate new membership terms for Britain.
The meeting was forced into extra time on Friday as Prime Minister David Cameron struggled for a deal he could sell to sceptical British voters in a referendum.
"The political risks are hard to price in at the moment ... There is clearly little appetite in building fresh long and/or short positions before more clarity on the issue," Ipek Ozkardeskaya, analyst at London Capital Group, said.
The UK Oil and Gas index fell 1.4 percent, the top sectoral decliner, after oil prices dropped by more than $US1 a barrel as talk of a plan by some producers to freeze output levels was tempered by continued concerns of an oversupplied market after a record build in US crude inventories.
The sector put pressure on the broader UK stock market, with some investors booking profits following this week's strong gains.
"We've (had) a very strong rally, a fair bit of short-covering no doubt ... However, now the market is looking to consolidate," Dafydd Davies, partner at Charles Hanover Investments, said.
Bucking Friday's trend, shares in bottling company Coca-Cola HBC rose 2.8 percent after it reported a profit lift following a return to growth for the first time in five years in its established markets.
Engineering company Essentra, a mid-cap company supplying specialty plastic and packaging components, gained 9.1 percent after strong full-year results.