A large number of flights to and from Adelaide, Canberra and Sydney are expected to be cancelled today.

Airservices and meteorologists are closely monitoring a new ash cloud with the potential to seriously impact air travel in much of south-east Australia in the next 12-48 hours.

Depending on wind and other weather conditions, the ash also has the potential to affect flights to and from Tasmania and Melbourne tomorrow (Wednesday) or earlier, Airservices said.

According to the air traffic provider, the ash cloud is denser and larger than that which caused widespread disruption to flights last week. It is also predicted to linger longer over south-east Australia.

It is spread in a large band below the Australian continent and is predicted to continue to move to the north-east and east in coming days.

The ash cloud, which is between 20,000 and 40,000ft (6-13km), is also expected to cause some flowon effects to the national air traffic network.

The ash is from the original eruption of the Cordón Caulle volcano in Southern Chile on 4 June and has now circumnavigated the globe one and a half times. It is therefore particularly persistent in the atmosphere and likely to cause ongoing disruption to the air traffic network.

Airservices National Operations Centre in Canberra, together with meteorologists and the Bureau of Meteorology’s Volcanic Ash Advisory Centre (VAAC) in Darwin, are continuing to monitoring the movement of the ash plume and provide advice to the aviation industry.

Travellers are advised to contact airlines for more specific and up to date information.

Virgin Australia has suspended all services into and out of Adelaide and Mildura on Tuesday, 21 June 2011, because of the return of a volcanic ash plume from Chilean volcano, Cordon Caulle. The airline said it will also suspend all services into and out of Canberra from 1.00pm AEST.

Group Executive Operations, Sean Donohue, said the latest advice from the Bureau of Meteorology and the Volcanic Ash Advisory Centre necessitates the suspension flights to the cities until further notice.

“The current forecast suggests the ash plume will be below 20,000 feet over Adelaide and Mildura tomorrow. With this in mind we are suspending these services tomorrow,” Mr Donohue said.

Qantas earlier cancelled 25 flights in and out of Adelaide and Port Lincoln between 6.30am and 2pm, while Jetstar cancelled eight Adelaide flights today (to and from Sydney, Melbourne, Brisbane and to Perth).

The airline says it will reassess the situation this afternoon, suggesting that Melbourne services may also be affected at some time today.