Nepal is considering a ban on tourists trekking alone in the Himalayas, officials said Wednesday, after several women foreign visitors were attacked or have disappeared.

Solo travellers would have to be accompanied by at least one porter or guide under proposals being discussed by the Maoist-led caretaker government, tourism ministry spokesman Bal Krishna Ghimire told AFP.

"Isolated cases of disappearances and killing of trekkers have tarnished the image of the country. We think that the compulsory arrangement of a tourist guide for a trekker will ensure their security," he said.

Ghimire declined to speculate on when the new policy may come into force.

An estimated 40 percent of foreign visitors to Nepal come to trek and the majority head to the Annapurna, Langtang, Helambu or Khumbu regions.

Although there is already a requirement for groups to have a guide, it has never been compulsory for independent travellers.

But a growing number of assaults in the Himalayan national parks has led to US Embassy and British Foreign Office warnings against trekking alone.

Belgian Debbie Maveau, 23, was missing for 10 days before her badly decomposed body was found decapitated in June beneath a hiking trail in the Langtang National Park, on the Tibetan border.

American Lena Sessions, also 23, was hiking solo in December in Langtang when she was threatened with sexual assault by a masked man wielding a knife. She managed to escape.

The incident came a week after a South Korean woman was assaulted nearby.

British 27-year-old Zisimos Souflas disappeared in April while travelling alone in Khumbu, while American Aubrey Sacco, then 23, went missing two years ago after telling her family she would be hiking in Langtang. nepalnews.com