Thu Oct 1, 2009 12:45pm IST

BEIJING (Reuters) - China's air force deployed a "magic-like" range of chemicals and technology to clear Beijing's smoggy air for a grand parade marking the 60th anniversary of Communist China, state media said on Thursday.

Chemists and officials worked for weeks on the country's most ambitious ever attempt at weather modification, with air force technicians fanning out across the region to help teams operate complex equipment, the official Xinhua agency said.

The evening before the parade chemicals were fired into the hazy skies, and a light rain washed the city clean.

Surrounding provinces had already been loading clouds with silver iodide and dry ice, to try and force rain to fall before it reached Beijing, the report added.

"Only a handful of countries in the world could organise such large-scale, magic-like weather modification," said Cui Lianqing, a senior air force meteorologist who said the parade operation was the largest in China's history.

Contingency plans allowed for the teams to use one kind of chemicals to bring down rain in the parade area, and another to hold it off, he told Xinhua.

China has been researching cloud seeding and other weather manipulation techniques since the 1950s, but in the past has met with mixed success.

The opening to last year's flagship Olympic Games fell on a day when skies looked hazy despite a raft of anti-pollution and weather manipulation measures.

And a deluge in 2005 forced a hasty last-minute venue change for an outdoor ceremony featuring top Chinese leaders, even after organisers had been promised China could guarantee dry weather.

Cui said this year's plans dwarfed those for the Olympics, but despite their success he said there was still room for further improvements.

"The technology we have mastered so far could only allow us to modify the weather to a limited extent," he told Xinhua.

"There are many uncertainties up in the sky."

(Reporting by Emma Graham-Harrison; Editing by Jeremy Laurence)