US President Barack Obama has signed into law new sanctions against Iran intended to impede¹ the development of its nuclear programme.

为阻止伊朗发展核武器的企图，美国总统奥巴马将对其实行的新制裁签署成为法律。

The measures, which penalise（惩罚） foreign companies that trade with Iran, were overwhelmingly（压倒地） approved by US Congress last week.

Mr Obama said the sanctions would strike "at the heart" of Iran's ability to fund and develop nuclear programmes.

Iran says its nuclear industry is for peaceful purposes; the West disagrees.

The bill targets those firms that supply Iran's Revolutionary Guards or contribute to the country's energy industry, including foreign companies that provide finance, insurance, or shipping² services.

Mr Obama said: "We are showing the Iranian government that its actions have consequences, and if it persists, the pressure will continue to mount, and its isolation³ will continue to deepen.

"There should be no doubt - the United States and the international community are determined⁴ to prevent Iran from acquiring nuclear weapons."

Mr Obama noted⁵ that Iran had rejected the offer of dialogue and engagement he had made on taking office last year.

"To date, Iran has chosen the path of defiance⁶（蔑视，反抗） ," he said. "That is why we have steadily⁷ built a broader and deeper coalition⁸ of nations to pressure the Iranian government."

Tehran denies seeking to acquire nuclear weapons.

Assets frozen

Last month, the UN Security Council voted to impose a fourth round of sanctions on Tehran for failing to halt（停止） its nuclear enrichment programme.

They include tighter finance curbs⁹ and an expanded arms embargo¹⁰（武器禁运） , but not the crippling（造成严重后果的） sanctions the US had wanted.

Iran's President Mahmoud Ahmadinejad dismissed those sanctions as a "used handkerchief" fit for the dustbin.

Three earlier rounds of UN sanctions have blocked trade of "sensitive nuclear material", frozen the financial assets of those involved in Iran's nuclear activities, banned all of Iran's arms exports and encouraged scrutiny¹¹（监视，审查） of the dealings of Iranian banks.