Women in Indonesia's devastated Aceh province who lost their homes in the December 26th earthquake and tsunami face sexual attacks in relief camps, Oxfam said, as it warned of long-term social dislocation.
More than 220,000 were killed or are still missing and, three months after the disaster, half a million are homeless. In some villages the earthquake and tsunami killed up to four times as many women as men, Oxfam, an international aid group, said after a survey of villages.
It said findings were similar in India and Sri Lanka.
"In some villages it now appears that up to 80 per cent of those killed were women. This disproportionate impact will lead to problems for years to come," Becky Buell, Oxfam's policy director, said in an Oxfam report calling for more effort to protect women.
"We are already hearing about rapes, harassment and forced early marriages."
Today marked three months since the disaster, which killed an estimated 182,000 people around the Indian Ocean with a further 106,000 reported missing. Aid pledges from around the world have topped $5 billion.
Women's activists in Aceh said most camps for tsunami survivors did not have facilities segregated by sex, and men and women from different families often sleep under the same tent. "Many female survivors who lost their male relatives also sleep in these tents and they do not have protection. Rapes then happen and after that the women are put into some sort of exile so that people won't talk," said Wanti Maulidar, head of Women's Solidarity of Aceh.
Oxfam said the gender imbalance needed to be factored into reconstruction, as women feared they would face more work to look after extended family and pressure to have more children.
Other tsunami-hit nations such as Sri Lanka faced the same issues but Oxfam said there were variations, such as the absence of alcohol abuse from staunchly Muslim Aceh.
In southern Sri Lanka today, Buddhist monks in saffron robes marked three months since the tragedy by laying out 2,500 oil lamps in the coastal village of Peraliya, where the tsunami slammed into a train, killing more than a 1,000 people on board as well as hundreds of others living nearby.