FTSE up as mining, oil shares resist crude slump

* FTSE 100 up 0.5 percent, reverses earlier losses

* Energy stocks recover after fresh lows for oil

* Miners up, gold at 3-week high

* Ashtead falls sharply, tracks weaker U.S. peer (Updates with prices rises)

By Atul Prakash and Lionel Laurent

LONDON, Jan 6 (Reuters) - Britain's top share index rose on Tuesday afternoon, reversing earlier losses and tracking a pan-European recovery in energy and mining stocks despite commodity-market concerns as oil prices hit 5-1/2-year lows.

The rise came after a survey also showed growth in Britain's dominant services sector suffered its steepest decline in more than three years in December, marking another disappointing piece of economic data.

The FTSE 100 index was up 0.5 percent at 1527 GMT, broadly in line with the pan-European FTSEurofirst 300 index.

Miners such as Randgold, Anglo American (LSE: AAL.L - news) and Fresnillo (Other OTC: FNLPF - news) were among the top performers, up 3.7 to 5 percent, with gold climbing to a 3-week high as investors sought safety from recent sell-offs in equity and commodity markets.

The battered oil and gas sector also enjoyed a slight recovery, with BG Group (LSE: BG.L - news) , BP and Tullow Oil (LSE: TLW.L - news) up between 1.9 and 3.2 percent, with analysts pointing to a pause in selling rather than a fundamental change in outlook.

"It's difficult to be positive on energy shares near-term as oil prices fall, with no clear turnaround catalyst yet visible," said Keith Bowman, an equity analyst at Hargreaves Lansdown (LSE: HL.L - news) .

Shares (Dusseldorf: DI6.DU - news) of Ashtead, a UK industrial-equipment-hire company, plunged 6.4 percent. The followed an 11 percent slide for its U.S. rival United Rentals (NYSE: URI - news) after a broker downgraded it.

Both companies are exposed to the energy industry, analysts say, which is suffering from oil's slide to 5- 1/2-year lows.

Also putting pressure on the market is concern over Greece, where a Jan. 25 election might vault the left-wing Syriza party into power. The party threatens to renounce the country's bailout agreement with the European Union, raising the risk of a sovereign default.

"Continuing uncertainty surrounding the upcoming Greek election and the potential fall-out of Greece possibly leaving the euro is spooking investors," said Peregrine & Black senior analyst Markus Huber. (Editing by Alison Williams)