Ballooning debt to pay for new electric trains and the inner city rail link has earned the Auckland Council a negative watch on its credit rating.
International credit ratings agency Standard & Poor's is getting the jitters about Mayor Len Brown's ambitious transport plans and warned of a credit downgrade from AA to AA-.
The agency has talking to the council about plans to significantly increase capital expenditure, particularly for transport, in Mr Brown's first 10-year budget.
Credit analyst Anna Hughes said it was unclear to the agency how much of this spending would be done with borrowed money, but council projections suggested that the council's debt level would exceed 170 per cent of operating revenue by 2013 and 200 per cent by 2015.
"We expected to resolve the credit watch during the next 90 days as the council finalises its draft 2012 long-term plan.