SADDAM Hussein is trying to close the 60-70 day ''weather window'' for a land campaign against Iraq by dangling the possibility of the return of UN weapons' inspectors as a delaying tactic, Pentagon sources say.

The ideal time to launch an attack runs from late November through to late March, when desert temperatures dip to between 58 and 70 degrees, a vital consideration for troops who would have to wear stifling chemical warfare protective suits over their uniforms.

The standard, charcoal-lined ''Noddy'' suit is topped off with a gas mask, three pairs of gloves including a rubber set, and rubber over-boots. The entire body must be covered in an airtight seal to avoid nerve-gas or germ warfare contamination.

Because it is impossible to remove any of the kit in target areas, men cannot drink and quickly succumb to heat exhaustion.

By April, the average desert temperatures soar rapidly back up to the mid-80s Fahrenheit, peaking at more than 100 degrees from June to September.

The campaigning season is also restricted by the onset of Ramadan, the Muslim holy month, which begins in early November. It was widely accepted before Iraq's tactical announcement that UN inspection teams might be readmitted that the US would postpone any military assault until at least December to avoid inflaming Islamic sensibilities.

US forces have improved their ability to fight in high temperatures by staging annual exercises in Kuwait in early summer, but new, lightweight protective suits now being developed would not be ready even for a war next year.

Admiral Steve Baker, a retired US naval commander with extensive Gulf experience, said yesterday: ''The heat would not stop an attack being mounted, but it would complicate it immensely. It really slows down movement. Couple that with the need to respond to potential nerve-gas and biowar threats and armoured combat ceases to be a fast-moving process.

''If we discovered that Saddam had a useable nuclear weapon, we could mount a campaign in June at the height of summer. It would not, however, be a preferred option. Weather has always been the defining factor in military affairs in the region.''

A winter campaign, now in jeopardy, also has the advantage of longer hours of darkness. US technology and night-vision devices would give an American-led force a powerful advantage over their poorly-equipped Iraqi opponents.

A Pentagon source said: ''Realistically, there is a 60/70-day regional window of opportunity for a ground campaign. Saddam knows that. It's why he's trying to derail the planning process. His goal is personal survival, and he obviously figures he can buy himself the best part of another year if he blocks an invasion this time round.

''The White House might still decide to order an attack in unfavourable conditions, but the decision-making also has to take into account international opinion, regional Islamic interests, and above all the price we might have to pay in casualties by fighting at a distinct disadvantage.

''The key to rapid success and minimum military and civilian losses is exploitation of superior technology, application of maximum force, and timing. Saddam may just have won the first round in that respect.''

A senior British military source added: ''Saddam doesn't actually have to use any of his chemical or biological hardware. The threat of its use is enough

to restrict severely the deployment and movement of allied forces.''