New Zealand's petrol supply has gone down, but officials say supply remains within normal levels.

Just released figures are current to Sunday, when there were 48.7 days of petrol supply, down from 49.9 last Wednesday. 

But diesel supply is up slightly, at 46.4 days compared to 45.5 on Wednesday.

Jet fuel's at 43.4 days, down from 44.7. 

Starboard Maritime Intelligence analyst Mark Douglas says there's more tankers on the way to New Zealand, so there's no significant disruption just yet.

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