The FTSE 100 <.FTSE> ended up 4.91 points, or 0.1 percent, at 6,410.26 points, its highest close so far for 2016 and narrowly beating a closing high of 6,405.35 hit in the previous session.

The index is up more than 16 percent from 3-1/2 year lows in February, but remains down 10 percent from the all-time high it attained a year ago.

Figures showing that U.S. crude stockpiles rose slightly less than expected last week boosted the index, which has a heavy weighting in commodities stocks.

Shares in oil majors Royal Dutch Shell and BP (>> BP plc) rose 0.7 percent and 0.2 percent respectively, with the energy sector adding around 4 points to the FTSE 100.

Mining companies, the top risers, also helped to push the index higher, rallying on a series of price target upgrades from Investec, which said a bottom of the market had been tested and found.

Anglo American (>> Anglo American plc) climbed 5.2 percent, while Antofagasta (>> Antofagasta plc), BHP Billiton (>> BHP Billiton plc), Rio Tinto (>> Rio Tinto plc) and Glencore (>> Glencore PLC) all gained between 0.4 percent and 3.9 percent.

"U.S. oil just crept into the black for the day as well ... Cue rise by the oil majors, and in fact anything commodity-related, as per the pattern seen of late, with mining shares taking heart from rebounds in minerals markets that they may not be even directly linked to," Ken Odeluga, market analyst at City Index, said in a note.

In negative territory, however, Hargreaves Lansdown (>> Hargreaves Lansdown PLC) was the top faller, down 4.4 percent. Traders said Swiss peer GAM's poorly received results had had an impact on the UK financial sector. It said turbulent market conditions were likely to continue to weigh on client sentiment and flows in the near term.

It was joined by bookmaker Paddy Power Betfair , which dropped 4.3 percent after Credit Suisse began coverage of the stock with an "underperform" rating.

The investment bank cited concerns that the benefits from a merger between Paddy Power and Betfair had been overplayed, and said the share price reaction was overdone.

"With regards to Paddy Power and Betfair, as both companies already had strong brands, high quality management teams and good product/technology offerings, we question the extent of the benefits from a merger," Credit Suisse analysts said in a note.

Among mid-cap companies, plus-size fashion retailer N Brown (>> N Brown Group plc) slumped 12.8 percent, its biggest daily loss in more than a year, after reporting weak first quarter results.

(Reporting by Alistair Smout; Editing by Gareth Jones)

By Kit Rees and Alistair Smout