Driven by fall in US crude stocks and conflict in the Middle East, oil prices sought a rise of more than a dollar, touching 2015 highs on Wednesday.

Brent crude increased by $1.36 to $68.88 a barrel by 0855 GMT. According to experts, US crude traded $1.51 higher at $61.91 a barrel, near an intraday high of $62.05.

"We haven't seen hedge funds and money managers to be as optimistic and bullish as they are currently. They are at their most bullish since July last year, when the oil market fundamentals haven't really changed that much", said Vyanne Lai, an oil analyst with National Australia Bank.

According to industry group the American Petroleum Institution (API), for the first time this year US crude oil stocks dropped and gave a raise to oil prices. As per API, overall stocks dropped by 1.5 million barrels. The US government's Energy Information Administration is going to issue official stockpiles data.

Libyan output is presently below 500,000 barrels per day and it is a third of what the country pumped before 2010. Oil prices also drew support because the dollar dropped 0.3% against a basket of currencies, on course for a fourth straight weekly loss.

According to Iran's Supreme Leader Ayatollah Ali Khamenei, Tehran would not participate in nuclear discussion if threatened with military force. Iran and world powers are putting efforts to meet a June 30 deadline for a final deal. Any break in discussion with the West and Iran would prolong any possible comeback of Iranian crude exports at full throttle. Oil's increase followed a rally of 20% for Brent and 25% for US crude prices in April.