Oil futures slid Wednesday as markets started to price in the impact on supplies of Iran’s historic deal with Western powers regarding the Islamic Republic’s nuclear program.

Oil futures slid Wednesday as markets started to price in the impact on supplies of Iran's historic deal with Western powers regarding the Islamic Republic's nuclear program.

Traders were keeping a watch also on US commercial oil inventories ahead of a weekly report Wednesday, and digesting upbeat Chinese economic growth data.

Brent North Sea crude for delivery in August shed 38 cents to stand at $58.13 a barrel in London midday deals.

US benchmark West Texas Intermediate for August dropped 35 cents to $52.69 compared with Tuesday's closing level.

The oil market had risen Tuesday as investors were confident it would take time for Iran to start exporting more crude to a market awash with supplies.

"It is gradually dawning on market participants that Iran will not be making any rapid return to the oil market even after the historic agreement," Commerzbank analysts said in a research note to clients.

"The agreement first has to be ratified by the UN and by the US Congress. Then Iran has to implement the conditions set out in the agreement, and the International Atomic Energy Agency has to confirm this in a report. Only then will sanctions be eased."

Iran and major world powers on Tuesday reached a deal to monitor Tehran's nuclear program, which the West says will curb its efforts to build a nuclear bomb.

Iran's compliance with the terms of the agreement will lead to a lifting of crippling Western economic sanctions which have restricted its key oil exports.

The negotiators gave no specific dates for the implementation timeframe, other than saying it would begin "upon conclusion of the negotiations".

Iran is exporting about one million barrels per day of crude, sharply down from the 2.2-2.3 million it was selling overseas before the sanctions were imposed in mid-2012, according to energy information provider Platts.

"Iran's oil and financial sanctions will be lifted with a phased deal struck on its nuclear program on July 14, but the market won't immediately see more crude," Platts said in a commentary.

"The market probably won't see any noticeable increase in Iranian crude supply until next year."

Elsewhere, the US government's Department of Energy is expected to reveal that American crude reserves fell 1.9 million barrels in the week ending July 10, according to analysts polled by Bloomberg.

That would signal strengthening demand in the world's biggest consumer of oil.

Gasoline or petrol inventories are expected to have increased by 450,000 barrels, while distillates -- including diesel and heating fuel -- are seen climbing 1.46 million barrels.

China, the world's biggest energy user, said Wednesday that its growth expanded 7.0 percent year-on-year in the second quarter -- beating expectations as months of central bank policy stimulus helped support the world's second-largest economy.

The gross domestic product figure announced by the National Bureau of Statistics (NBS) matched the 7.0 percent expansion in the first three months of this year, and exceeded the median forecast of 6.9 percent in an AFP survey of 14 economists.