A small sinkhole has opened up in central Wellington after a water main burst early today.

The northbound lane on Jervois Quay near Hunter Street has closed with flooding from incident, which happened about 6.15am, Inspector Dave Rose from central police communications said.

"It has undermined some of the footpath and road lane there.

"The council are on the scene and they're obviously going to have to do a little bit of work to isolate the pipe and reinstate the ground works."

The ASB building also suffered flooding, Mr Rose said.

There were traffic delays in the area and motorists were asked use an alternative route.

It would be "some time" before initial repairs would be made, he said.

Wellington City Council spokesman Clayton Anderson said the incident meant surrounding offices could be without water until about 3pm.

Council contractors had isolated the problem, which was thought to be a pipe that was laid about the year 1900, and had cordoned off an area from Hunter Street to Willeston Street.

Due to the location, it was likely to take at least half the day, possibly into mid-afternoon, before service was restored, Mr Anderson said.

Drivers were also urged to use caution as there was a great deal of silt on the road.

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