Indian police rounded up a group of homeless men Wednesday over the alleged gang-rape of a 51-year-old Danish tourist who lost her way near the main backpacker's area of the capital, officers said.

The woman approached the suspects for directions early on Tuesday evening while trying to return to her hotel in the bustling Paharganj district of New Delhi, reportedly after visiting a city museum.

Up to six "youngsters" allegedly assaulted and robbed the victim, who was travelling alone and had been in New Delhi since Monday after visiting the Taj Mahal, police and a receptionist at her hotel told AFP.

"We have detained a group of men and we are questioning them over the incident," special commissioner of police Deepak Mishra told AFP.

A senior investigating officer in the Paharganj police station told AFP on condition of anonymity that the victim was held hostage at knife-point for three hours and had been kicked and slapped.

Her mobile phone and cash were also stolen.

The alleged attack just minutes from Connaught Place in the heart of the capital is the latest involving a foreigner in India, and again raises questions about the safety of women in the world's second most populous country.

Last month, India marked the first anniversary of the death of the student who was gang-raped on a moving bus in the capital in an attack that sent shockwaves across the nation.

'Vagabond' attackers

The Danish victim refused to be medically examined and was clearly traumatised by the experience, but gave a detailed statement overnight in the presence of her country's ambassador, police said.

She has since left India.

"We have identified around four to six people who are the prime suspects in the case," the investigating policeman said, adding that they appeared to be "vagabonds".

"She told us that the attackers were mostly youngsters," he added.

The crime scene was inside the grounds of the Railway Officers Club on State Entry Road with the victim saying she was dragged to a secluded area shrouded by trees near a statue, police said.

A police forensic team visited on Wednesday morning and police are in possession of the clothes the victim was wearing at the time of the attack.

Kuldeep Singh, a receptionist at the victim's hotel, said the woman had appeared calm when she returned at about 8:30pm (1500 GMT) but then confided in a fellow traveller.

"She first came to me at the reception desk and told me that she needed 200 rupees to give to the auto driver as she had been robbed," Singh said.

Danish ambassador Freddy Svane told AFP the embassy was providing assistance to the woman, but declined to give further details.

The case comes after a Polish woman was allegedly drugged and raped by a taxi driver earlier this month while travelling with her two-year-old daughter to New Delhi.

Female tourists afraid

Women tourists in Paharganj said they were aware of past cases and the new incident had rung alarm bells.

"I felt very unsafe with walking the streets and seeing what you see and everybody staring at you, but you can’t not travel to India because of it," said Jessica Orpwood, a 21-year-old student backpacker from New Zealand.

Protests over sexual violence in the last year have prompted India's parliament to toughen laws for rapists and other offenders, while other judicial and police reforms that have encouraged women to report attacks.

But daily accounts of brutal assaults continue to be reported in the country's newspapers.

A schoolgirl was raped by eight men in the eastern city of Ranchi this week while they held her male friend, the Hindustan Times reported on Wednesday.

A judge last month sentenced three Nepalese men to 20 years in jail for the gang-rape of a US tourist in June in the northern state of Himachal Pradesh.

Six men were sentenced to life in prison last July for the gang-rape and robbery of a 39-year-old Swiss woman cyclist who had been holidaying in the central state of Madhya Pradesh.

Bridget McCaffrey, another backpacker from New Zealand, said news of the latest assault had come as a shock "but considering in the last year what’s been happening in India with women, maybe not so much."

"If I were to come back to India it would be with a group or with my partner again, I wouldn’t be coming alone as a single female traveller," she said.