Accusations that Iran is hampering the UN atomic watchdog's investigation into its nuclear programme by vetoing key inspectors look set to dominate the IAEA's week-long meeting this week.

The 35-member board of the International Atomic Energy Agency is to convene for its traditional September meeting starting Monday with a packed agenda.

In addition to topics ranging from nuclear security to the agency's two-yearly programme performance report, governors will be formally notified of the appointment of a number of deputy directors general, including the successor to the IAEA's top inspector Olli Heinonen, who resigned last month.

And the board will also prepare for the agency's annual general conference -- which brings together all 151 member states -- being held the following week and where Arab states are expected to target Israel over its assumed nuclear arsenal.

Once more, however, it will be the IAEA's latest reports on Iran and Syria, circulated to member states last week, that will likely be the focus of attention at the board meeting.

The Iran report complained that the Islamic republic was hampering the agency's work by barring experienced inspectors.

It found that Tehran was continuing to increase its stockpile of both low-enriched and higher-enriched uranium in defiance of UN orders to halt any such activity until the IAEA can determine the true nature of Iran's nuclear programme.

It said that Iran was still refusing to answer questions about possible military dimensions to its work.

And although the head of Tehran's atomic agency Ali Akhbar Salehi boasted last month that sites had been chosen for 10 new uranium enrichment facilities, Iran has not provided the agency with any information about those sites, as it is obliged to do under its safeguards agreement.

On Thursday, Iranian opposition group the National Council of Resistance of Iran (NCRI) claimed Iran was building a new uranium enrichment site in Abyek, about 120 kilometres (70 miles) northwest of Tehran.

But Iran denied the allegation and experts have also expressed scepticism about the reliability of the information.

Diplomats close to the IAEA said the Iran report showed that Tehran, instead of helping to allay Western fears about a possible covert nuclear weapons programme, was only undermining any confidence in the proclaimed peaceful nature of its work.

The so-called "de-designation" of inspectors was "troubling", even if Iran was perfectly within its rights to vet IAEA inspectors coming into the country, as every member state is, the diplomats said.

It was the first time that experienced inspectors who had already been working in a country for a long time had suddenly had their permits revoked, they said, suggesting it was a way for Iran to intimidate and dissuade inspectors from asking too many awkward questions.

The IAEA's latest report on Syria was similarly frustrating, diplomats said.

It showed that Damascus was still stonewalling, two years after the agency launched an investigation into allegations that Syria had been building a covert nuclear reactor at a remote desert site with the help of North Korea until it was bombed by Israel in September 2007.

The IAEA could press for a mandatory "special inspection" to resolve the allegations. But diplomats said there was much debate within the agency over whether to resort to such a measure at this stage.

The last time special inspection powers were invoked was in the case of North Korea in 1993.

In the end, the hardline communist state still denied the IAEA access and went on to develop a nuclear bomb capacity in secret.

Looking ahead to the IAEA's general conference starting September 20, diplomats said Western countries would seek to dissuade Arab states from tabling a resolution targeting Israel.

Last year, they secured narrow backing for a resolution calling on the Jewish state to join the nuclear Non-Proliferation Treaty. And diplomats suggest a similar text could be put forward again this year.

But Western countries are concerned that singling out Israel, widely believed to be the only power in the region with nuclear weapons, would be divisive.

And it could jeopardise the agreement reached in New York in May for a regional conference in 2012 to advance the goal of a nuclear-free Middle East, the diplomats argued.