A temporary ban on work near Ararat, in the state's west, has been extended until February until a full legal challenge - a test of Aboriginal heritage protections - can be heard.

Djab Wurrung elder Marjorie Thorpe is trying to stop duplication works she says will damage six trees of cultural heritage and their surrounding areas of significance to the local Indigenous community.

Other sections of the duplication project have been completed but a 12.5km stretch of the highway - the main route between Melbourne and Adelaide - is being held up.

Authorities say while the challengers have identified six trees of significance, they have only earmarked one for removal.

Justice Jacinta Forbes said she accepted that a permanent injunction on any upgrade works was unlikely, but noted more limited relief might be possible.

She agreed to grant a temporary injunction until a Supreme Court trial, expected to occur in February.

Justice Forbes said there were a number of activities proposed by the state government and road authorities as not being caught up in a complete ban on road construction and associated works.

She said she would hear from lawyers next on what activities would be covered by the injunction.

Australian Associated Press