St Ouen honorary police closed the area on Thursday morning over fears that more of the structure would fall into the sea.
Centenier Richard Buchanan said the area could be closed for some time.
‘I am no structural engineer but is not good towards the northern end of the pier – it is likely to continue to erode away.
‘There is a big crack across the car park and some of the railings have fallen away.’
Meanwhile, Adam Querée, owner of the adjacent Colleen’s Café, said the business was due to reopen this Saturday after Christmas and despite the closure of the parking area, there was still a large number of parking spaces in the top car park.