Advances in the development of fast, portable detectors and on-the-spot analysis methods bring a major boost to the capabilities of the UN inspectors as they start their mission in Iraq.

Their task, to look for evidence of the possession and production of nuclear, chemical and biological weapons in at least 400 sites, will be like looking for a needle in a huge haystack.

This is a huge step forward in assisting the inspectors, although you still cannot beat the man on the ground Chris Cobb-Smith, former UN weapons inspector

And to make it harder, they have only 60 days from the first inspection before they have to report to the Security Council.

The new detectors, analytical equipment and tamper-proof cameras will be key factors in determining whether they are able to carry out their tasks within such a tight deadline.

Among the array of gadgets they will have at their disposal are:

• Spy satellites - can photograph sites in greater detail than ever
• Alex - an alloy detector capable of finding materials with nuclear applications
• Hanaa - a hand-held analyser which can detect anthrax or plague in 15 minutes
• Improved radar - can detect materials buried up to 100 feet (30 metres) underground
• Digital tamper-proof cameras - can be set up to film sites before and after inspections

The new technology should make inspections more efficient, and should enable inspectors to analyse materials on the spot.

Multi-level inspections

Former UN weapons inspector Chris Cobb-Smith told BBC News Online: "This is a huge step forward in assisting the inspectors, although you still cannot beat the man on the ground".

He stressed that the equipment would give a boost to the teams as long as they carried out the inspections "like a military operation and ensured that they got access to everything they wanted to look at".

Hans Blix (right) expects Iraq to cooperate

The range of technology available to the UN inspection team, Unmovic, will enable them to search and analyse from satellites in space down to inspectors on the ground taking and analysing swabs from the walls, floors and equipment at suspect sites.

Developments in spy satellite technology mean that even commercial satellites have the ability to reveal much more detail than ever before of factories, buildings and arsenals.

Radar can detect targets above and below ground. If materials have been buried, ground-penetrating radar can detect them deep beneath the surface.

Inspectors on the ground will have an array of hand-held or portable sensors than can detect the alloys used in making nuclear devices, rapidly analyse swabs to detect chemical or germ warfare traces and detect suspect materials in the air, water and soil.

Before setting off for Iraq, the chief weapons inspector, Hans Blix, said that "powerful new means of verification" would be used during the mission.

Jacques Baute, chief inspector for the International Atomic Energy Agency (IAEA), says one key new device is a hand-held Ranger sensor, which can detect gamma radiation and provides a display on an LCD screen.

Personnel are key

But new technology alone is not enough.

A spokesman for the IAEA said that trained and experienced staff were vital.

Iraq has been preparing for the UN's arrival

"A trained person can walk into a facility and immediately red flags will go up in his mind ... things are too new here, there's a fresh coat of paint, this piece of equipment shouldn't be over there with those other ones," says Mark Gwozdecky of the IAEA.

But the inspectors will now be able to delve more deeply if they are suspicious about a site and will be in a position to analyse samples there and then.

In the past, swabs or other samples have had to be sent back to a main inspection centre or even flown to the United States or Europe for analysis.

This slowed inspections down and gave greater room for error or disagreement if laboratories in different countries were used to analyse samples.

Chris Cobb-Smith told the BBC that, if you can get a rapid result of tests on materials while the inspection team is still at a site, you can then verify the result in front of that team and be on the spot to make a judgement on the next step.

Inspectors will not have to leave sites to have samples analysed, thereby reducing opportunities to tamper with an already inspected site.

A new generation of digital cameras will also be available to the inspectors.

These are tamper-proof and can be used to monitor suspect sites in the absence of the inspection teams.

But the Iraqis have extensive experience of weapons inspections and some experts believe they will have honed their skills to conceal anything incriminating from Unmovic.

So, even with better equipment, the inspectors have no easy task ahead of them if they are to meet the expectations being placed on their mission.