An International Atomic Energy Agency (IAEA) team began a three-day visit on Sunday to try to advance efforts to resolve a row about nuclear work which Iran says is for making electricity but the West suspects is aimed at seeking a nuclear weapon.

Tensions with the West rose this month when Washington and the European Union imposed the toughest sanctions yet in a drive to force Tehran to provide more information on its nuclear program. The measures take direct aim at the ability of OPEC's second biggest oil exporter to sell its crude.

The Mehr news agency quoted Foreign Minister Ali Akbar Salehi as saying during a trip to Ethiopia: "We are very optimistic about the outcome of the IAEA delegation's visit to Iran ... Their questions will be answered during this visit,"

"We have nothing to hide and Iran has no clandestine (nuclear) activities."

Iran's parliament speaker, Ali Larijani, warned the IAEA team to carry out a "logical, professional and technical" job or suffer the consequences.

"This visit is a test for the IAEA. The route for further cooperation will be open if the team carries out its duties professionally," said , state media reported.

"Otherwise, if the IAEA turns into a tool (for major powers to pressure Iran), then Iran will have no choice but to consider a new framework in its ties with the agency."

Iran's parliament in the past has approved bills to oblige the government to review its level of cooperation with the IAEA. However, Iran's top officials have always underlined the importance of preserving ties with the watchdog body.

Before departing from Vienna, IAEA Deputy Director General Herman Nackaerts hoped for the Islamic state to tackle the watchdog's concerns "regarding the possible military dimensions of Iran's nuclear program".