A traffic queue stretching about 17km from Auckland to Otahuhu formed this morning after a truck broke down on the Harbour Bridge and blocked a lane.

The New Zealand Transport Authority was warning motorists to avoid heading north over the bridge because only two lanes were open.

Later the NZTA tweeted the breakdown had been cleared and all four lanes were opened to traffic.

The agency expected the congestion, which stretched back along the Southern Motorway, would soon ease.