Iran hinted Tuesday that inspection of the Parchin military site by the International Atomic Energy Agency would be possible in the context of a "comprehensive agreement" that recognises its right to peaceful nuclear energy.

"We are ready to reach a comprehensive agreement with the (IAEA) in which the nuclear rights of our country, under the Non Proliferation Treaty, are recognised," foreign ministry spokesman Ramin Mehmanparast told reporters.

"Naturally under such agreement which includes the removal of ambiguities and concerns of the Agency, the issue of visiting Parchin military may be part of this agreement," Mehmanparast said at his weekly briefing.

His remarks came as an IAEA delegation headed for Tehran where they are due to meet Iranian officials on Wednesday for the eight round of talks in a year, and the third such trip in the past three months.

The UN nuclear watchdog will "work hard" to resolve differences with Iran over its nuclear programme at talks in Tehran, the body's chief inspector, Herman Nackaerts, told reporters at Vienna airport on Tuesday.

"Differences remain... we will work hard to try to resolve these differences," Nackaerts said as he boarded a plane for Tehran. "We will have good negotiations."

The IAEA wants Iran to grant it access to nuclear sites, particularly Parchin, as well as people and documents that can help provide information on its November 2011 report into Tehran's nuclear activities.

In the report, the IAEA said it had credible information that Iran had worked to develop nuclear weapons before 2003 and possibly again since then.

Tehran insists that its nuclear programme is for peaceful purposes.

The IAEA believes that activity relevant to nuclear weapons development took place at the Parchin military base near Tehran.

But the Islamic republic says the IAEA already visited Parchin twice in 2005 and found nothing untoward. The agency counters that new information obtained since then makes it want to go back.

The IAEA also says that because of activity at Parchin spotted by satellite, including moving "considerable" volumes of earth, its inspections there will be "seriously undermined" if it ever goes.

As a signatory of the NPT, Iran has to submit its nuclear facilities to inspection by the agency, but insists that Parchin is a military site and therefore not subject to the inspection.

burs/hkb/bpz