Indian officials have put the blame for the gang rape of a Swiss woman in the central Indian state of Madhya Pradesh on the victim and her husband.

State government home minister Uma Gupta said the incident, which he described as "unfortunate" for India, was partly the fault of the couple because they had not told police where they were going.

"When foreign tourists come, they should inform the SP (superintendent of police) about their plans," Gupta told NDTV.

"This is the system but it is not being followed. They had their tent in the outer area of the city. The incident should not have happened so we will think what more can be done for foreign tourists."

The chief minister of the state, Shivraj Chouthan, said if the police had been informed of the visitors' plans they could have provided proper protection.

Insp Avnesh Budholiya said the tourists had been careless in travelling to a remote part of the country they knew little about.

"No one stops there," he said. "Why did they choose that place? They were in the wrong place at the wrong time. They would have passed a police station on the way to the area they camped in. They should have stopped and asked about places to sleep."

The opposition in Madhya Pradesh demanded the resignation of the home minister for his "insensitive comments".

The couple were on a cycling tour when they were attacked by a group of men allegedly from the Datia region, 200 miles south of New Delhi.

Although the police have detained 20 people, the exact number of perpetrators is not clear and may be as high as eight.

The assailants "tied up the man and gang-raped the woman in his presence," senior police official D K Arya told The Hindu newspaper.