POLICE are searching for missing Victorian girl Larni Edwards, who is believed to be travelling through South Australia with an adult man.

Larni, 13, disappeared on Tuesday after leaving her home at Ultima, about 22km south-west of Swan Hill, in country Victoria, about 8am to catch the school bus to Swan Hill.

Police believe she is travelling with Dean Patrick James, 36, and say they are concerned for her welfare.

Larni withdrew money at an ATM and travelled to Bendigo, then Ballarat.

The Herald Sun reported that police believe Larni and Mr James communicated via the internet and said she was "groomed" before they met together.

"There has been a confirmed sighting of Larni in Ballarat, where she was seen in the company of a 36-year-old Sebastopol man, Dean Patrick James," a police spokesman said.

"Police believe Larni and Dean James are travelling in a blue 1997 Ford station wagon possibly bearing false registration plates QZW540."

Larni was described as 160cm tall, with a thin build, shoulder-length, brown hair, a fair complexion and freckles.

When last seen, she was wearing a school uniform with a navy blue, v-neck jumper, white polo shirt and blue, yellow-and-grey skirt.

Mr James was described as 180cm tall, about 90kg, with a solid build, cropped hair and unshaven. He was wearing a khaki t-shirt and green camouflage cargo pants.

A picture released by police shows Mr James with a full beard but he now has cropped hair and a trimmed his beard, police said.

Anyone with information on the pair should immediately contact police on the emergency 000 number, SA Police 131 444 or Bank SA Crime Stoppers 1800 333 000 or www.sa.crimestoppers.com.au.