Air New Zealand has had to divert and cancel flights between Auckland and Nuku'alofa, after a volcanic eruption near Tonga.

After erupting intermittently for a week or so, the Hunga Ha'apai volcano has released a large ash plume that's risen to about 30,000 feet.

Civil Aviation Authority's chief meteorological officer Peter Lechner says if there isn't another eruption, things could return to normal for airlines by tonight.

He says it's not a huge eruption by world standards - but clearly it's having an effect on local aviation and international flights.

Air New Zealand has scheduled extra services later in the week to accommodate those customers who've been impacted, so long as the ash clears.