Evacuation at Sydney food factory

Workers have been evacuated from a food processing plant on Sydney's lower north shore after a grain silo threatened to explode.

Emergency services rushed to the factory in Lane Cove on Tuesday night amid reports the temperature inside the silo had risen beyond safe levels.

Staff were evacuated and firefighters pumped carbon dioxide into the silo to try and lower the temperature.

"If the temperature increases over the next few hours we could have some problems," said Fire and Rescue NSW Inspector Ian Krimmer.

"If the temperature remains static or decreases we'll be a lot happier."

Emergency services are expected to remain at the site for most of the evening.