Mr Nackaerts led a team that had three days of talks in Iran, but did not visit nuclear sites
UN nuclear inspectors back from a trip to Iran to discuss its contested nuclear programme have said the country is "committed" to "resolving all outstanding issues".
The International Atomic Energy Agency's deputy director-general said they hoped to return to the country.
Inspectors described their visit as positive but said there was still work to do.
Iran insists its uranium enrichment work is peaceful in purpose.
The IAEA's Herman Nackaerts said his organisation and the Iranians were both determined to address all outstanding matters.
"But of course there is still a lot of work to be done and so we have planned another trip in the very near future," he told reporters as he landed in Vienna, the organisation's headquarters.
A few days ago, Iran described its three days of talks with the IAEA inspectors as "positive and constructive". According to state media the IAEA team did not inspect any nuclear sites.
The inspectors' evaluation of their visit may form part of the next written report on Iran's nuclear programme, expected later in February.
Tehran says its nuclear activities are simply for electricity generation.
But last November, the IAEA said it had information suggesting Iran had carried out tests "relevant to the development of a nuclear explosive device".
Since then, the US and the European Union have imposed a series of sanctions against Iran, including measures targeting the country's lucrative oil industry
1 February 2012 | Source BBC News
