Washington, Jan 13 (IANS): US President on Friday opted to extend sanctions relief provided to Iran as part of the 2015 nuclear deal, but he warned European allies that he would pull out of the pact unless its "terrible flaws" are corrected.

The US Congress requires the president to approve sanctions waivers related to the deal - signed by Iran, the US, the United Kingdom, Russia, France, Germany, China and the European Union - every 120 days.

"Today, I am waiving the application of certain nuclear sanctions, but only in order to secure our European allies' agreement to fix the terrible flaws of the Iran nuclear deal. This is a last chance," Donald Trump said in a statement, Efe reported.

"In the absence of such an agreement, the United States will not again waive sanctions in order to stay in the Iran nuclear deal. And if at any time I judge that such an agreement is not within reach, I will withdraw from the deal immediately," he warned.

Trump had threatened in October to withdraw from the Iran nuclear deal unless its defects were corrected, either through negotiations with other signatories of the pact or unilaterally by the US Congress.

The president said Friday he hoped to reach a supplementary agreement with the US's European allies to "impose new multilateral sanctions if Iran develops or tests long-range missiles, thwarts inspections (of its nuclear installations) or makes progress toward a nuclear weapon."

That follow-on agreement must eliminate sunset provisions included in the 2015 agreement, according to the White House, which objects to the fact some restrictions on Iran's nuclear program expire after between 10 and 25 years.

When Trump threatened in October to abandon the Iran deal, the UK, France and Germany said in a joint statement that they remained committed to the pact, formally known as the Joint Comprehensive Plan of Action, and to its full implementation by all sides.

The European Union also has not given any sign of wanting to renegotiate the deal.

Besides issuing an ultimatum to Europe, Trump also said he wanted an amended US law on the Iran nuclear deal that would include "trigger points" that, if violated by the Persian nation, would automatically lead to the reimposition of US sanctions.

On Friday, Iranian Foreign Minister Mohammad Javad Zarif responded to Trump's remarks by saying on Twitter that the nuclear deal was not renegotiable and that the US must comply with it fully.

Trump's stance on the accord "amounts to desperate attempts to undermine a solid multilateral agreement," he added.