NEW DELHI • A woman in the United States has told police in India she was gang-raped at a top hotel in the Indian capital during a visit earlier this year - the latest in a series of alleged sexual assaults against tourists.

Delhi police launched a formal investigation last Saturday after receiving a direct complaint from the woman, who had initially contacted them through an e-mail from a US-based non-governmental organisation.

"The police have registered a case of rape and will now verify all aspects of the woman's complaint," Joint Commissioner of Police Mukesh Meena told news agency Agence France-Presse.

Foreign Minister Sushma Swaraj urged police to "bring the guilty to book" after initial media reports of the incident. "I have also asked the Indian ambassador in the US to contact the victim and assure her that we will not spare the guilty," she tweeted last Saturday.

Local media reports, citing police sources, said the woman had travelled to India in April but cut her visit short after the alleged crime.

The woman has complained that her local tour guide, who had access to her room, gave her a spiked bottle of water and raped her with four other acquaintances inside her hotel room.

"She said that after having water from the bottle, she started feeling dizzy. Then four other men... entered the room and locked it," said a report in the Sunday Times of India.

Police are now verifying the woman's timeline and tracking the suspects, including checking security camera footage from the hotel.

Sexual attacks on tourists in India are widespread, with several Western countries warning visitors about the risk.

A 35-year-old Japanese tourist was raped in southern India last month.

Last year, a Japanese woman was drugged and raped by a tourist guide in the western city of Jaipur, less than a month after six men gang-raped a 22-year-old Japanese tourist in the eastern city of Kolkata.

An Indian court in June this year convicted five men of gang-raping a 52-year-old Danish tourist in New Delhi in 2014. They were jailed for life.

India is also facing intense scrutiny over its efforts to curb violence against women in general, following the fatal gang rape of a medical student in New Delhi in December 2012, which sparked a global outcry.

AGENCE FRANCE-PRESSE