In a terrifying attack, the men went to the woman’s home in Dulibadzimu township in Zimbabwe’s border town of Beitbridge.

Posing as detectives, they ordered her to accompany them to the police station. Once outside, they dragged her to a bushy area on the banks of the Limpopo River, where they raped her – and fell asleep.

The woman sneaked away to alert her sister and security guards, who returned and carried out a citizens’ arrest before police arrived.

The attack shows just how crime is spinning out of control in once-peaceful Zimbabwe.

The number of armed robberies and assaults has surged since a unity government between president Robert Mugabe’s ZANU-PF and the former opposition Movement for Democratic Change was formed in February.

Regular bank raids, hijackings and supermarket shootouts are prompting unfavourable comparisons with neighbouring South Africa.

The latest bank to be targeted was Barclays, in the second city of Bulawayo, last Friday. Six men with pistols burst into the building and terrified tellers before getting away with $50,000, 126,000 rand and £500. Kingdom Bank, in Harare, has been targeted twice.

In Harare’s Glen Norah township, residents are keeping to a 6pm curfew after a mobile phone trader was beaten to death by muggers last month.

Giles Mutsekwa, Zimbabwe’s home affairs minister, believes former diamond diggers and dealers, who were removed from the Marange fields in a controversial security operation last year, are behind the crime. "They are turning to this crime because they have to maintain their lifestyles," he said. "It’s a cause for concern."

Foreign nationals who entered Zimbabwe to take part in the diamond trade were also involved, he claimed.

Analysts say that the surge in crime is linked to super-high inflation; when Zimbabwe’s worthless dollar was in circulation, criminals found it more lucrative to "money-burn" – conduct illicit deals in foreign currency over the internet – than steal money that would lose its value in a matter of hours.

Canny criminals are trading on the fact that Zimbabwean businesspeople, wary of central bank raids on their accounts, are bank-shy. George Guvamatanga, the managing director of Barclays Zimbabwe, said last week that Zimbabwe banks held just £294 million in deposits, while £619 million was kept out of the system, in homes, safes or offices.

Jane Mutasa, a Harare businesswoman, was robbed at gunpoint of£12,382 and her Mercedes Benz S350 in Harare’s quiet Greystone Park suburb, which is better known for its pair of roaming leopards than as a haven for robbers.

"I was ordered to get out of my vehicle by one of the accused persons, who was wearing a police uniform and armed with a pistol," she told a court last week.

There is speculation some of attacks are politically-motivated. A gang armed with AK47s raided the home of Priscilla Misihairabwi-Mushonga, the MDC’s minister for regional integration, who was in Brussels at the time. The men attacked and badly injured her husband, Dr Christopher Mushonga, who is in his seventies.

Family members told the Standard newspaper the attackers taunted Dr Mushonga: "You are from the MDC, we are Zanu-PF and we have been sent to beat you up."

And questions are being asked as to why 45 armed robbery suspects were released on bail last month – when rights activists and MDC officials are regularly denied bail.