Ash from a volcano in Chile has returned to parts of New Zealand on Wednesday, further disrupting air travel after a two-day respite.
The volcano, part of the Puyehue-Cordon Caulle chain, has been erupting since the beginning of June.
The cloud of volcanic ash is slowly moving up the South Island on Wednesday at an altitude of between 20,000 and 40,000 feet.
Qantas has cancelled all its trans-Tasman flights to and from Christchurch from 2pm after a sudden wind change pushed the ash cloud back over New Zealand.
Jetstar has also grounded its flights in and out of Christchurch.
Both Australian airlines had already suspended flights to and from Queenstown for the rest of Wednesday.
Jetstar says it has not had to add extra services to clear the backlog of travellers affected by disruptions caused by the same ash cloud last week.
Air New Zealand flights are continuing on schedule.
Civil Aviation Authority meteorologist Peter Lechner says the cloud is moving slowly and will probably lie just north of Christchurch by midnight on Wednesday.
Mr Lechner says the cloud is sitting at between an altitude of 20,000 and 40,000 feet, which still leaves plenty of room to fly under it.
It is likely the ash cloud will linger for at least another day.