Iran will get a first installment around February 1 of $550 million of $4.2 billion being unblocked under a six-month landmark nuclear deal with the West, a U.S. official said Sunday.

"The installment schedule starts on Feb. 1 and the payments are evenly distributed" across 180 days, a senior U.S. administration official told Agence France Presse.

EU foreign policy chief Catherine Ashton will visit five Gulf nations on a tour of the region next week focusing on the war in Syria, Iran's disputed nuclear program and Israel-Palestinian peace efforts.

Ashton will visit the United Arab Emirates, Kuwait, Saudi Arabia, Oman and Qatar on the trip which runs until January 16, according to a diplomatic source.

A senior commander of Iran's powerful Revolutionary Guards said Saturday that Hizbullah has dramatically improved its missile capabilities and can now pinpoint targets anywhere in Israel.

Gen. Amir Ali Hajizadeh said Israelis will see Hizbullah's new might should a war break out.

Iranian nuclear chief Ali Akbar Salehi said the first phase of talks with the U.N. nuclear watchdog will be finished by early February, English-language Press TV website reported Friday.

Earlier on Friday, Iran and world powers agreed on how to implement a landmark November deal on containing Tehran's nuclear program, but it must still be approved by each country before it can take effect.

The White House on Friday declined to renew its previous prediction that a Senate bill slapping new sanctions on Iran, which it fears could scupper nuclear talks, would not pass the Senate.

President Barack Obama's spokesman Jay Carney warned however that the bill would be detrimental to the drive to resolve the nuclear showdown with Tehran short of war.

Israeli Prime Minister Benjamin Netanyahu and Iran's President Hassan Rouhani, whose countries are arch-foes, are both set to attend the World Economic Forum this month, organizers said Friday.

WEF spokeswoman Michele Mischler confirmed to Agence France Presse that both leaders would be at the January 22-25 annual gathering of top politicians and business leaders in the plush Swiss ski resort of Davos.

Iran and the EU have found solutions to all their disagreements after talks on how to implement a deal on containing Tehran's nuclear program, Iranian deputy chief negotiator Abbas Araqchi said Friday, as the EU reported "very good progress."

"We had two days of good, constructive and intense negotiations in which we made good progress," Araqchi was quoted by state television as saying at the end of two days of talks in Geneva.

Iranian President Hassan Rouhani said Thursday a Syrian peace conference planned for later this month will fail if Tehran, Damascus' main regional ally, does not participate, media reported.

The remarks came ahead of a meeting Monday at which Russia and the United States are to discuss Tehran's possible involvement in the talks set to start in Montreux, Switzerland on January 22.

Iran and world powers met Thursday to discuss how to implement a landmark deal aimed at containing Tehran's nuclear drive, less than two weeks before the agreement is due to take effect.

Iranian, EU and U.S. negotiators gathered in Geneva for their highest-level talks since hammering out the groundbreaking November 24 deal.

Russian President Vladimir Putin and his Iranian counterpart Hassan Rouhani on Thursday discussed the Islamic republic's nuclear negotiations with world powers and Syria peace talks, the Kremlin said.

The leaders discussed "current international issues, including the situation in Syria in the context of preparations for the Geneva 2 conference, and the implementation of agreements on the Iranian nuclear program," the Kremlin said in a statement that did not specify who initiated the telephone call.