(Close): The FTSE 100 closed 1.16% higher, with energy shares climbing on the strength of a recovery in the oil price earlier in the day.
By the close of trading in London, however, the price of Brent crude was down 0.8% at $71.72 a barrel.
Among energy stocks, Tullow Oil rose 5.8%, BP shares were up 4.9% and Royal Dutch Shell "A" shares gained 4.1%.
The rebound pulled the FTSE 100 higher, with the benchmark index up 77.47 points at 6,733.84.
Royal Mail shares fell 2.6% after regulator Ofcom said the universal postal service was not under threat.
Ofcom also said it would not impose new conditions on Royal Mail's competitors.
Friends Life shares were 2.4% higher after it agreed to be bought by Aviva in a £5.6bn deal. Shares in Aviva rose 0.1%.
On the currency markets, the pound fell 0.6% against the dollar to $1.5636 and rose slightly against the euro to €1.2623.
