Sydney locals rally against WestConnex

Hundreds of protesters have closed a major Sydney road to rally against the state government's plan to build an interchange in the city's inner west.

About 400 people gathered on Campbell Street in St Peters on Saturday to call on the Baird government not to connect the busy road with the M5.

About 80 properties are being bought by state authorities to cater for the thousands of extra cars expected in the area under the proposed WestConnex project.

Premier Mike Baird said he sympathised with residents who were worried about disruptions while the project was built, but stressed it would bring "huge" long-term benefits.

St Peters resident Chris White said he was concerned the plan would introduce an extra 10,000 cars a day into the area.

"This place will become a ghetto," he told AAP.

"The roads are already choked.

"The only way that you could move the traffic through is going to be by killing the whole inner west."

Greens state MP Mehreen Faruqi said WestConnex was flawed and would not relieve traffic congestion.

"If the M5 extension of the WestConnex is built, thousands more cars will pour into local streets and really change the character of this area," Dr Faruqi said.