Iran on Monday confirmed that nuclear talks this week with world powers would take place in Istanbul, dropping public reservations over that city as venue following a sharp-worded row with Turkey.

If the Istanbul negotiations with the P5+1 group -- the five permanent UN Security Council members and Germany -- on Saturday prove fruitful, another round of talks could be held in Baghdad, the office of Iran's chief nuclear negotiator, Saeed Jalili, said in a statement.

"The first round of talks between Iran and the P5+1 will be held on April 14 in Istanbul and a second round will be held in Baghdad" at a date to be mutually agreed, said the statement from the Supreme National Security Council headed by Jalili.

The confirmation appeared to put an end to Iran's see-sawing position on Istanbul that cast a cloud of doubt over the talks in recent days.

Tehran had at first enthusiastically embraced the Turkish city as the ideal venue for the talks. US Secretary of State Hillary Clinton even went as far as to declare that city as the host of the talks.

But last week Iranian officials and politicians suddenly went cold on it, saying Turkey's support of the opposition in Syria -- Iran's chief ally -- excluded Istanbul as a venue. They proposed Baghdad instead, or possibly Damascus or Beijing.

That earned an unexpectedly virulent rebuke from Turkish Prime Minister Recep Tayyip Erdogan, who had visited Tehran just days earlier to discuss the talks with Iran's leaders.

"It is necessary to act honestly," Erdogan said last Thursday.

"They (the Iranians) continue to lose prestige in the world because of a lack of honesty," he stormed.

By Monday, Iran had once again come around to accepting Istanbul as the venue.

In Brussels, a spokesman for EU foreign policy chief Catherine Ashton, who is representing the P5+1, said "we have agreed to launch talks in Istanbul on April 14."

He gave no indication, though, of any discussion about further rounds of talks, or whether they would be held in Baghdad.

Jalili's statement underlined that Iran had set aside its reservations and was back on board with Istanbul.

But the incident added to strains already apparent in bilateral relations.

Turkey, which lies over Iran's northern border, sources a third of its oil imports from Iran, and it has in the past two years sought to position itself as a diplomatic bridge between the Islamic republic and the West.

But Ankara's decision to install an early warning system for a NATO-led anti-missile shield seen as protection from Iranian missiles sparked unease in Tehran last year.

And in recent weeks, Turkey has joined US-imposed sanctions by cutting Iranian oil imports by 20 percent, triggering further animosity.

It is Turkey's position on Syria, though, that has greatly irritated Iran.

On April 1, Istanbul served as the venue for a "Friends of Syria" conference gathering countries sympathetic to rebels seeking to overthrow the regime of Syrian President Bashar al-Assad.

Iran has repeatedly vowed to stand by Assad, and has been giving him political and material support as he cracks down on unrest. The United Nations says more than 9,000 people have been killed in Syria since the violence started a year ago.