A Swiss cyclist was gang-raped after she and her husband were attacked while camping in India, police said.

Authorities detained and questioned 13 men in connection with the attack, which occurred on Friday as the couple camped out in a forest in Madhya Pradesh state after cycling from the temple town of Orchha, local police officer RK Gurjar said.

The men beat the couple and gang-raped the 39-year old woman, he said. They also stole the couple's mobile phone, a laptop computer and 10,000 rupees (£123).

The woman was treated at a hospital in the nearby city of Gwalior.

A photo showed the woman – her identity concealed with a hood – walking while being escorted by police to the hospital.

Police detained 13 men and questioned them, Gurjar said. Six of the men were released after questioning. No other details were immediately available.

Indian television stations showed scores of police searching the forest where the attack occurred.

The Swiss foreign ministry spokesman Tilman Renz described the case as "deeply disturbing" and said Swiss diplomats were assisting the couple.

The diplomats called on Indian authorities "to do everything to quickly find the perpetrators so that they can be held accountable," Renz said in a statement.

Last month, the Swiss government issued a travel notice for India that included a warning about "increasing numbers of rapes and other sexual offenses" in the country.

India has experienced outrage and widespread protests against attacks on women since December's fatal gang-rape of a young woman on a bus in New Delhi, the capital. The crime horrified Indians and set off nationwide protests about India's treatment of women, spurring the government to hurry through a new package of laws.

One of six suspects in the December attack was found dead in a New Delhi jail this past week. Authorities said he hanged himself, but his family and lawyer insisted foul play was involved. A magistrate is investigating. Four other men and a juvenile remain on trial for the attack.