Iraqi authorities yesterday helped ensure the smooth passage of a three-man balloon attempting to become the first to fly non-stop around the world - but Beijing was reported to be insisting it must keep away from China.
Officials at mission control in a hangar at Geneva airport said the huge Breitling Orbiter-II, with the European crew's pressurised cabin slung below, was zipping along eastwards over Iran in steady winds after crossing Iraq.
Despite tension in the country amid the US and British military build-up in the region over the Iraqi refusal to allow full-scale United Nations weapons inspections, there were no problems from Baghdad for the balloon.
"The Iraqi air traffic controllers were very polite and very helpful," a mission spokesman quoted a Swiss crew-member, Mr Bertrand Piccard, as reporting.
Officials said last-minute efforts were under way through various channels to win a change of mind from the Chinese, who had earlier flatly refused to give the balloon clearance arguing they could not guarantee its safety.
"We hope they understand that we are not dangerous," said one mission spokesman. "A lot of people are trying to help us and we hope we can announce a good outcome on Monday."
The Orbiter, designed in Britain, had originally hoped to avoid Iraq but winds had taken it south after crossing Turkey and into the "no-fly" zone in the north maintained by a US-led coalition since the 1991 Gulf War.
Mr Piccard and his colleagues - a Belgian pilot, Mr Wim Verstraeten, and a British engineer, Mr Andy Elson - had no permission to enter Iraqi air space, but this came through quickly from the control tower at Baghdad airport.
"We had been very concerned about Iraq, but they said they had no objection to the flight," the mission director, Mr Alan Noble, said. "They handled it perfectly normally."
The balloon, on the fifth day of its flight since taking off from the Swiss Alps last Wednesday, took just four hours to cross Iraqi territory heading towards Iran - which had already said it was welcome.
After Iran, it will cross into Afghanistan and Pakistan where winds would normally have been expected to carry it over the Himalayas into China. However, if Beijing does not consent, the balloon will have to drop below jet stream winds and try to fly south.
Even if successful, this would add at least two days to what was originally planned as a 14-day voyage - stretching fuel supplies close to their limit.
Mission control said the balloon was clipping along at some 70 miles an hour at a height of around 9,000 metres and the crew hoped to be above Tehran by midday today.
With a leaky hatch repaired on Saturday after Mr Elson climbed outside, the crew was able to pressurise the cabin and then fly much higher to take advantage of the jet stream for a key part of their 25,000 km journey.
Controllers operating from a hangar at Geneva airport said the Orbiter could now fly at altitudes of between 9,000 and 14,000 metres (five to eight miles), far higher than during the agonisingly slow first days of the journey.
If it crosses Asia safely, it will head out over the Pacific towards the western seaboard of the United States and onward towards the Atlantic, going for an eventual touchdown somewhere in North Africa.
The British entrepreneur, Mr Richard Branson, who plans to set off from Morocco in a few days in a rival attempt to circle the world, wished the Breitling Orbiter-II team good luck.
Since the season started last month, every attempt to set ballooning's biggest record has so far failed, either for technical reasons, bad weather or a combination of both.