"The Istanbul talks were a success and we hope that the Baghdad meeting also will be a success, and if we took one step forward in Istanbul surely, with God's help, we will take several steps ahead in Baghdad," Salehi said in a joint press conference with his Armenian counterpart.

"We were at the beginning of the end regarding (Iran's) nuclear issue in Istanbul, and we hope in a not-so-far future we will witness the closure of this manufactured dossier," he added.

Iran is to meet representatives of the so-called P5+1 group, comprising the five permanent UN Security Council members plus Germany, in Iraq's capital for the second round of talks which were revived this month in Istanbul after a 15-month impasse.

The Istanbul talks sought to establish a non-confrontational tone allowing the more substantial Baghdad session to go ahead.

Iran is going into the meeting with the aim of rolling back Western economic sanctions imposed to pressure it over its nuclear activities. Tehran denies Western allegations that the activities include efforts to develop nuclear weapons capability.

The P5+1, though, are seeking ways to verify Iran's programme is exclusively peaceful.

Discussions are seen as likely to focus on whether Iran should be permitted to continue enriching uranium to 20 percent, several steps short of the 90 percent needed for military uses.

Los Angeles Times newspaper last Friday quoted US officials as saying Washington could consider allowing Tehran to enrich uranium to five percent only -- a compromise from a previous position ruling out any enrichment.

The UN Security Council has imposed four rounds of its own sanctions on Iran because of suspicions about its nuclear programme, aired by the International Atomic Energy Agency in November 2011 and reiterated in February.

Salehi declined to go into details on the likely content of the Baghdad talks.

"Please allow the details to surface after the Baghdad meeting. There are a number of analyses and views going around which are premature to talk about," he said.

Western threats of war "are so frequent that it would seem to indicate an attack or invasion will certainly not occur," Ramin Mehmanparast, a spokesman and vice minister at the Iranian foreign ministry, told journalists.

Israel has repeatedly raised the possibility of attacking Iran in order to pre-empt it from acquiring a nuclear bomb, a move Tehran insists is not on its agenda.

"At the moment, Iran has the greatest defence capability in its history. Whoever wants to attack our country, will meet with our very firm response," Mehmanparast said during a visit to the Polish capital for bilateral talks.

"This is why our adversary completely understands that should it attack our country, it will itself become the subject of a great tragedy," he said, adding: "This is why the possibility of war is very, very weak."

Mehmanparast also slammed a slew of tough Western sanctions on Iran's trade and banking sectors aimed at stifling its nuclear program as "completely illegal and unjustified because our nation has not committed any crime."

But the sanctions have had the welcome "side effect of making Iran increasingly self-sufficient in many economic sectors," he noted.

"If we were to make light of it, we could thank the US and European states for levelling sanctions because they have actually spurred economic growth" in the oil-rich state, he added.

"When growth in many Western countries is either negative or around zero, in Iran we have 6.2 percent growth in GDP," said the official, who holds an MBA from Canada's Carlton University.

A series of reforms eliminating fuel and other subsidies have so far freed up $150 billion (113 billion euros) for investment over the last two years in the country of 74 million, the spokesman added.

Within two years all subsidies are to be cut within two years, which Mehmanparast said would free up some $130 billion to $150 billion for investment.

"This year our national budget is 500 billion dollars. This indicates our country's economic potential -- the potential of a country experiencing sanctions," he said.

Mehmanparast discounted, as "very far from the truth," fresh allegations by a US Republican congressman and Western experts that Iran is preparing to launch a potentially crippling cyber-attack on the United States and its allies.

The official also termed a "media hoax" a popular Facebook anti-war campaign dubbed "Israel loves Iran."

Recently launched by an Israeli graphic artist opposed to Israel's sabre-rattling against Iran, the page features an anti-war cyber poster blitz and has so far garnered 63,300 "likes" and a lively response from Iranian Internet users.