We were surprised by the arrival of the UN inspectors, but we co-operated fully with them... they told us there were no problems

Haitham Mahmoud, al-Tahadi factory

The inspectors are using state-of-the-art technology to try to find out whether Iraq has any weapons of mass destruction.

Their findings could determine whether the US carries out its threat to lead a military assault on the country.

UN Secretary General Kofi Annan said the work had got off to "a fairly good start" and urged Baghdad to sustain co-operation.

The inspections were authorised by the UN Security Council in a resolution unanimously agreed earlier this month, which aims to compel Iraq to disarm or face "serious consequences".

'No problems'

Two teams set off from the UN's Baghdad offices at the former Canal Hotel at 0530 GMT. One drove to a site north-east of the capital, the other to a graphite plant in al-Amariyah, 40 kilometres south-west of Baghdad.

Inspectors' remit and task

Unrestricted inspection rights Can report any obstruction to the UN First task to assess infrastructure left behind in 1998 They will set up monitoring equipment Are able to take witnesses out of Iraq Click here to read Q&A on inspections

The BBC's Ben Brown in Baghdad says the inspectors caused traffic chaos as they drove off at high speed in white Land Cruisers, pursued by journalists.

The team our correspondent was following visited the al-Tahadi factory, in the al-Rashad suburb about 13 kilometres (8 miles) north-east of the capital.

The plant's director, Haitham Mahmoud, showed journalists around and told them the factory made machine parts for use in oil and cement production - nothing to do with weapons of mass destruction.

"We were surprised by the arrival of the UN inspectors, but we co-operated fully with them," he said.

The inspectors left after three hours. "They told us there were no problems," the director said.

The inspectors themselves have not released any details of their visit.

Both sites are reported to have been inspected in the 1990s, before UN inspectors left the country complaining that Iraqi officials were obstructing their work.

As the inspections began, air raid sirens sounded over Baghdad.

Iraqi officials say they were set off by Western planes flying over the city.

The Iraqi capital is just north of a southern no-fly zone regularly patrolled by US and British planes.

The UN has flown in tons of equipment

But both US and UK officials denied there had been any activity over Baghdad.

In the days ahead, the UN inspectors are expected to spread out over Iraq in search of mobile laboratories, underground factories and other signs of banned Iraqi weapons production.

Under the terms of the resolution, Baghdad has until 8 December to produce a list of any nuclear, chemical or biological weapons in its arsenal - the accuracy of which weapons inspectors will be asked to verify.

	:	Iraq spotlight
Click to see maps of Iraq's suspected weapons sites

The Iraqi leadership has vehemently denied possessing any such weapons.

The resolution also demands that Iraq provide complete access to all sites, including mosques and Saddam Hussein's presidential palaces - locations which inspectors were frequently turned away from in the 1990s.

"The Iraqis understand that the games that we saw in the 1990s will not be tolerated by us or the international community," said Melissa Fleming, spokeswoman for the International Atomic Energy Agency (IAEA).

Evidence required

Although the inspectors have refused to reveal their itinerary, it is thought they will concentrate first on installations that were inspected in the 1990s, to see if equipment left there is still working.

Eventually there will be 100 inspectors working in Iraq at any one time - including biologists, chemists, missile and ordnance experts, engineers and physicists.

Correspondents say it could take the team up to a year to produce a final verdict on whether Iraq has a weapons programme, and if so, how dangerous it is.

On top of the evidence his team collects, chief weapons inspector Hans Blix has told Baghdad that it must provide "convincing" proof that it no longer has weapons of mass destruction.