Homicide squad detectives have joined a major search for a German backpacker missing since June.

Carolina Wilga, 26, has been travelling Australia for two years but has not made contact with family or friends or been seen for 10 days.

WATCH THE VIDEO ABOVE: German backpacker Carolina Wilga missing northeast of Perth.

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She was last seen in person in Toodyay, an hour northeast of Perth, on Saturday, June 28, when she visited a convenience store on Stirling Tce near the intersection of Goomalling-Toodyay Rd.

Wilga was then captured on CCTV in Beacon, a remote town more than 300km northeast of the city in WA’s Wheatbelt region, a day later.

“We haven’t heard from her since then — that was on June 29,” WA Police Commissioner Col Blanch said on Wednesday.

The tourist is known to reside mainly in hostels. Her phone is not currently switched on.

“We are very concerned for her welfare,” Blanch said.

A woman who said she was the 26-year-old’s mum pleaded for information.

“I’m her mother and need her help, as I can’t do much from Germany,” she commented on a post by WA Police.

“Carolina is still sorely missed. If anyone has any information, please contact the police. Please keep your eyes open.”

Carolina Wilga was last seen on June 29. Credit: WA Police

Wilga is known to travel in a distinctive 1995 Mitsubishi Delica van. Credit: WA Police

WA Police Commissioner Col Blanch said police are 'very concerned' for the backpacker’s welfare. Credit: 7NEWS

Police air wing has joined a “very large search and rescue” operation which now includes homicide detectives.

“They either went yesterday or they’re going today,” Blanch said.

“They are investigating, not that it’s a homicide at this point, but we want our very best capabilities to investigate something that is very concerning to us.”

Wilga is travelling in a distinctive 1995 Mitsubishi Delica van, with the WA registration 1HDS 330.

“I would ask everyone to have a look at what that looks like and keep an eye out for it,” Blanch said.

Wilga has brown eyes, a slim build and several tattoos “including one which depicts symbols on her left arm”.

Anyone with information about her whereabouts or footage of Beacon and the surrounding Wheatbelt area between June 29 and July 4 should should contact Crime Stoppers.