The six vans, all but one which are heavily branded, were taken from the charity's Kew campus on Saturday night.

The theft means training and services in the new year will be heavily disrupted, and there will be delays for Victorians waiting to be paired with their much-needed guide dogs.

"We thank our generous donors who continue to support our vital work and condemn whoever is behind this despicable theft," a spokesman said in a statement.

Police are on site investigating.

Australian Associated Press