SYDNEY, Australia — Already essentially shut out of the United States, the Chinese technology giant Huawei is scrambling to salvage its reputation in another country where growing worries over spying and security could hurt its chances at a big chunk of business.

In an unusual letter to politicians in Australia made public this week, Huawei defended its status as a longtime supplier of networking gear and other equipment to the country’s biggest telecommunications companies. The letter came after news reports that Australian politicians were likely to shut the firm out of a potentially lucrative contract to upgrade the nation’s mobile network over security concerns. It also followed growing concerns among Australian leaders about Chinese influence in the country.

Barring the company from bidding on fifth-generation, or 5G, telecom networks would be “ill informed” and “not based on facts,” Huawei said in its letter.

“To completely exclude Huawei from 5G in Australia means excluding Huawei from the entire Australian market,” it said. “We don’t believe this would be in Australia’s best interest.”