FTSE 100 index extended gains on Thursday on news Greece will finally conclude its debt swap agreement. Oil shares and miners provided the biggest upside contribution to the index. Petrofac Ltd rallied 3.7% after J.P. Morgan Cazenove raised stock's rating from neutral to overweight, citing regained confidence in 2013 earnings growth. Other crude providers also advanced on surging oil prices. BP PLC gained 0.8% and Royal Dutch Shell PLC soared 1.6%. At the moment of writing FTSE 100 index trades 1.18% or 68.27 points higher at 5,859.68.