Continuing controversy around the announcement dubbed Bridges' 10 Bridges includes the national road funding agency saying the Government might have to find alternative ways to pay for the project.
The 10 Bridges scheme revealed during the Northland byelection campaign by Transport Minister Simon Bridges might not meet New Zealand Transport Agency (NZTA) funding criteria.
Conservationists are alarmed that widening one of the bridges could destroy two landmark, protected kauri trees in the Waipoua Forest.
But not all 10 bridges on Northland's state highways are currently in NZTA's sights, the agency's Auckland and Northland Regional Director Ernst Zollner said.
NZTA was informed about the announcement the day before the Government pledged to spend up to $69 million widening the bridges over the next six years, he said.