A Sydney council says the state government is overturning its block on a developer's plans to build a 120-metre tower, despite it exceeding height restrictions by at least 70 metres.

Chinese-backed property giant Auswin TWT is submitting a proposal for a 120-metre tower block on Chandos Street in St Leonards.

Overview of the St Leonards restrictions

That far exceeds North Sydney council's planned maximum height of between 45 and 50 metres for the area.

The council argues the building would overturn years of planning for how the suburb would be laid out and literally put its parks in the shade. But the decision on whether to allow the structure has been taken out of its hands.