The administrator appointed by the Baird government to run the newly merged Inner West Council, Richard Pearson, has written to residents vowing to "tirelessly" oppose the $16.8 billion WestConnex​ road project.

Mr Pearson was spat upon by a protester in May while trying to hold the council's inaugural meeting, which was disrupted by opponents of the forced merger and the motorway.

The protests followed Greens MP for Newtown, Jenny Leong, disclosing that in a meeting with Mr Pearson he said the new Inner West Council's position on WestConnex was "yet to be determined".

This was despite the councils that were forcibly merged - Leichhardt, Marrickville and Ashfield - being vehemently opposed.