KISUMU, Kenya — Hundreds of women and children, including boys as young as 5, have been gang-raped in a wave of sexual violence that has swept Kenya in the aftermath of last week’s disputed presidential election.

As ethnic hatred mounts in a country teetering on the brink of catastrophe, disturbing reports are emerging that angry mobs are adding rape to their arsenal of revenge.

At a hospital for women in the Nairobi suburb of Hurlingham, doctors said they had treated 24 women and 13 girls over the past four days. Three boys were also admitted after being repeatedly sodomized.

“Most of them have been gangraped, one of them by 10 men,” the hospital’s matron Rahab Ngugi said.

“We believe we only know about a fraction of cases because most people have no transport to get to hospitals or are still trapped because of the security situation.”

The vast majority of the victims had been assaulted in their own homes, and all had been targeted because of their tribe, the doctors said.

Most were members of President Kibaki’s Kikuyu tribe, attacked in Nairobi’s slums by other ethnic groups who support Raila Odinga, his Luo challenger.

The mobs had smashed their way into their homes, the women told doctors.

Attacking everyone they found inside with machetes and clubs, the youths raped them in front of their husbands, some of whom were later killed.

Aid workers said they had received reports of similar attacks across the country, although no statistics are available.

It was not just in Nairobi’s slums that sexual violence has been reported.

As opposition protesters attempted to march to a rally in the center of the city yesterday, a British woman in the prosperous suburb of Kilimani told the Daily Telegraph that she had witnessed an apparent sexual attack on a well-dressed young woman from the balcony of her home.

As mobs set fire to a nearby petrol station and police opened fire in the air, three young men took advantage of the mayhem to grab a slim woman of about 20, dressed in white jeans and a blue top, who appeared to have been inadvertently caught up in the violence. “As they advanced on her, she started backing away,” the British woman said. “She was begging them in Swahili, saying ‘please, please, please’ over and over again.

“They took her behind a wall, and I couldn’t see what happened, but I could hear the screams. I felt so helpless. It was too dangerous to go outside. If I had a gun, I would have gone and shot them, but I didn’t, so there was nothing I could do.”