A British backpacker was allegedly held captive and repeatedly raped in the Australian Outback in an ordeal lasting two months.

The woman was rescued by police who pulled over the car she was driving during a routine stop and found a man hiding in the back.

The 22-year-old was allegedly choked and assaulted while held against her will.

Queensland state police noticed the woman had facial injuries and appeared distressed when they pulled over her four-wheel drive during a routine traffic stop in the rural town of Mitchell on Sunday.

After the women stopped the car, officers found a 22-year-old man hiding in a storage alcove in the back of the vehicle.

Police said the two had met three months earlier in the north-east city of Cairns, where the man lived.

However, starting in January, police said the man began subjecting the woman to a series of violent assaults.

Police spokesperson CJ Roberts continued that the attacks occurred at various locations as the pair travelled 870 miles between Cairns and the outback town of Roma.

Detective Inspector Paul Hart told local media that "during the course of their travels throughout the state, a number of very serious offences have occurred.

"We would certainly say that what's happened to this lady is quite catastrophic so there are numerous supports that are being put in place to help her out during this period."

He continued that the woman had undergone "traumatic events" and since police believed the pair had previously been in a relationship they would also treat it as a "domestic incident".

A Foreign Office spokesman said: "We are supporting a British woman following an incident in Queensland and remain in contact with the local authorities."

The man was charged with four counts of rape, eight counts of assault, four counts of strangulation, two counts of deprivation of liberty, two counts of wilfull damage, one count of possessing dangerous drugs, one count of possessing drug utensils and one count of obstructing police.

The woman was treated for facial fractures, and cuts and bruising to her body. Police do not know how long she has been in the country for.