The chairman of the WestConnex Delivery Authority, Tony Shepherd, has slammed Labor's policy for the motorway, saying it would create more congestion in Sydney's inner west.

Under Labor's infrastructure policy announced on Thursday, the party says it would build new M4 and M5 East motorways to the north and south of the inner west but not connect them by tunnel - the third stage of the so-called WestConnex series of projects.

"Put in a damn tunnel": WestConnex chairman Tony Shepherd has slammed Labor's plan. Credit:Arsineh Houspian

"They are worried about those inner west suburbs but if you want to take the traffic off the roads in the inner west then the best way to do it is to put it in a damn tunnel," Mr Shepherd said.