Sydney CBD reopens after major gas leak forces shutdown

Sydney's CBD has been reopened after a major gas leak forced the closure of parts of the city.

A high-pressure gas leak has forced the closure of numerous Sydney CBD streets and Martin Place railway station for more than 10 hours. Source: AAP

Roads have been reopened around Sydney's Martin Place after a high-pressure gas main was ruptured by an excavator, closing down a section of the CBD.

A 200-metre exclusion zone was established around Martin Place on Friday after a gas main was ruptured during the construction of the Sydney Metro.

A group of 20 specialists worked overnight to fix the leak, with the road and rail closures lifted on Sunday morning.

Castlereagh Street, Elizabeth Street and Phillip Street were closed between Hunter and King Streets since the leak began about 10.30pm on Friday.

Martin Place train station was also closed during the incident.

Transport Minister Andrew Constance said the "very serious" incident occurred during preliminary works on the Sydney Metro site.

The minister said he was not "going to get into the ins and the outs" of which company was responsible.

The leak emitted a strong smell and deafening hissing sound, and a number of commercial buildings were evacuated with police and Hazmat crews brought in to assist.

SafeWork NSW is investigating the incident.