Oil firmed towards $72 a barrel on Friday, gaining for a third day, supported by views on equity markets that the economy may be stabilising and due to geopolitical concerns over key oil producers Iran and Nigeria.

U.S. crude rose 49 cents to $71.86 a barrel by 1358 GMT, having topped $72 earlier. London Brent crude gained 38 cents to $71.44.

Support came from disruptions to supply from Africa's top oil exporter Nigeria and political turmoil in Iran, the world's fourth largest producer, after its presidential election.

"We will see support continue to come from Iran and Nigeria. There is no immediate supply threat from Iran but in Nigeria (there) is an actual physical disruption," oil analyst Olivier Jakob of Petromatrix said.

Oil majors such as Royal Dutch Shell and Chevron have been targeted by militant sabotage attacks in Nigeria and their oil output has been dented.

The main militant group MEND said on Friday it had attacked another pipeline operated by Italy's Agip.

Jakob also said a weak dollar would provide support to the oil markets and traders would closely watch equity markets.

European shares were higher in morning trade, after Thursday's rally in Wall Street on signs of improvement in U.S. jobless claims.

Oil prices have nearly doubled since February on signs of a potential economic recovery but the pace of the rally has sparked concerns prices do not fully reflect improvements in oil fundamentals, and costly crude may hurt any nascent recovery.

U.S. President Barack Obama remains concerned about speculation in the oil markets even though he has not proposed concrete steps to rein it in, White House spokesman Robert Gibbs said on Thursday.