Newly ratified European Union sanctions targeting Iran's oil industry won't affect the progress of Tehran's nuclear program, the head of Iran's nuclear agency said on Thursday.

Late last month, EU governments formally approved an embargo on Iranian oil to start on July 1, dismissing calls by debt-ridden Greece for possible exemptions to help ease its economic crisis.

They also warned Iran that more pressure could be put in place if it continued to defy international demands for limits on its nuclear program, which they say is geared to developing weapons. Iran says its nuclear activity is only for electricity production and other peaceful ends.

"It is important that the Iranian leaders understand the resolve of the countries of the European Union on this," British Foreign Secretary William Hague said.

"We will go on intensifying the economic pressure until the world can be satisfied that Iran's nuclear program is for peaceful purposes," said Hague.

Referring to the newly approved sanctions, the head of the Atomic Energy Organization of Iran Fereidoun Abbasi told the country's state-run television station Press TV that the measures would not affect the progress of Iran's nuclear program.

"Many scientific and industrial technologies in the country, including the nuclear energy industry, have developed and achieved self-sufficiency despite the 30-year sanctions; therefore, the new sanctions will have no impact on the continuity of these activities,” Abbasi said.

The Iranian nuclear chief also said that Iranian experts "will counter the new sanctions and continue on their path of success."

Abbasi's comments came just days after Iran launched several long-range ballistic missiles, as part of an extensive military drill named Great Prophet 7.

According to the Press TV report, IRGC forces launched Shahab 1, 2, and 3 missiles, as well as the shorter ranged Khalij Fars, Tonda, Fateh , Zelzal and Qiam, targeting “simulations of the trans-regional forces’ airbases” in the northern region of Semnan Desert.

The launch came after, on Sunday, the commander of the Revolutionary Guards' aerospace division Brigadier General Amir-Ali Hajizadeh said that, by "firing missiles into these simulated bases, our commanders will assess the precision and the effectiveness of the warheads installed on the missiles."

The IRGC commander added that the drill was meant to show to “regional and trans-regional countries seeking adventurism that the Islamic Republic is determined to resist their bullying and will give a crushing and decisive response to any potential act of mischief."

The hardest measure to hit Iran yet

Iran's daily oil exports in July could fall below half the average shipped in 2011 before tough new Western sanctions stemmed the flow.

Japan and South Korea, among Iran's top oil buyers, have halted all Iranian imports this month due to sanctions imposed by Brussels on Sunday that aim to cut Iran's oil revenues and force Tehran to curb its disputed nuclear program.

Exports in July will fall to a maximum of 1.1 million barrels per day (bpd), said an industry source familiar with Iran's monthly shipping plans who declined to be named due to the sensitivity of the matter. Actual exports are likely to be less as top buyer China disputes freight costs with Iran's top tanker company, delaying the loading of cargoes set to flow east.

India could also reduce its July loadings as Iran struggles to find tankers of the size Indian refiners require do to port constraints. India is Iran's second largest customer.

Iran's exports have declined steadily this year from the 2.2 million bpd average in 2011 as its oil buyers cut imports to comply with U.S. and European Union sanctions.

Iran was estimated to have shipped between 1.2 million and 1.3 million bpd in June, industry sources said last month. 

July's cut translates into a loss of around e3.4 billion in monthly government revenue compared to a year ago, a major setback for Tehran as it struggles to contain spiraling consumers prices and mounting unemployment.

Although oil prices have fallen by around 20 percent in the last four months as other producers led by Saudi Arabia boost supplies, the market remains on edge over a possible supply disruption in Iran.

"If you think it's early enough to say that the market is going to easily cushion the impact of losing Iranian supplies, then you are just being plain foolish," said a Middle East-based trader with an oil major. "With Iran, you always have to stay alert."

As sales fall, Iran has been forced to store its unwanted crude on tankers in the Gulf. The country is expected to store at least 8.3 million barrels this month, double the amount the previous month, the source familiar with the shipping plans said.

Iran may need to cut back more of its estimated 2.95 million bpd crude output, already the lowest in nearly of a quarter century, as the nation runs out of onshore and offshore storage capacity. More than half of the ships owned by Iran's main oil shipper NITC are believed to already be storing crude.

The EU oil embargo has stopped European insurers, who dominate the maritime sector, from offering cover on Iranian crude. Industry watchers say the EU step has proven to the hardest hitting measure in the West's arsenal of sanctions aimed at Iran.

China and India are relying on Iran to use its own tankers to deliver oil to them, making Tehran liable for the insurance. South Korea has simply stopped importing Iran's oil for now. In Europe, Turkey and Italy were the only countries which continue to import Iranian oil after the start of the EU embargo.