Tourists and people at nearby restaurants have been moved away from the site (File)

About 500 people were evacuated from the Sydney Opera House on Tuesday after an excavator cut a gas line, triggering a leak.

Fire and Rescue New South Wales (NSW) was called to the Opera House at around 3 p.m. after the small excavator inadvertently cut the supply line, the Australian Broadcasting Corporation reported.

Tourists and people at nearby restaurants have been moved away from the site, and part of Macquarie Street has also been closed.

A specialist hazardous materials team is in the area and a 100-metre exclusion zone has been set up.

Fire and Rescue NSW is monitoring gas levels in the area and station officer Alex Cross said staff were waiting on specialist equipment to arrive.

"We need gas-rated machinery to be able to work in the vicinity of the gas leak. (If we didn't) there could be a spark that would lead to an explosion. It is not deemed safe at this point," Cross added.