Builders of the highly-anticipated Puhoi to Warkworth highway are keeping quiet about delays, and an opening date of the 880-million dollar project north of Auckland

Waka Kotahi is refusing to release its correspondence with its partner the Northern Express Group.

A total of 22 documents since Auckland went into lockdown on August 17 between the two parties have been withheld in full by Waka Kotahi, following an Official Information Act request by the Herald.

The highway was due to open this summer and when Covid-19 delayed the final earthwork season last summer, the opening date was pushed back to May this year.

When the project opens, it will chop 11 minutes off the current route.