Mr Murungi is an ally of President Mwai Kibaki

On Wednesday, Mr Murungi said donor criticism of the government's fight against corruption was "like raping a woman who is already willing".

"I unreservedly and sincerely apologize to all the women of Kenya who were offended by these remarks," he said.

Women's rights groups had staged noisy protests outside his office, demanding his resignation.

"It is trivialising rape and the fight against graft in one breath," activist Miriam Kahiga told the angry crowd.

Kenya's Human Rights Commission has also condemned the minister's "jibe".

'No thought'

"What is so entertaining about a 'willing' woman being raped?" Wanjiku Miano of the Kenyan Human Rights Commission asked in an open letter to Mr Murungi.

He's an embarrassment to the country and he has lost his value as a leader and lawmaker Miriam Kahiga Amnesty International, Kenya

"We use statistics to convince the world that rape is a crime against humanity and with no thought whatsoever, you negate our struggle with your insensible jibe."

Ms Kahiga, from Amnesty International, said Mr Murungi was "an embarrassment to the country".

In his statement, he said that as a "leader", he would continue to "promote women's rights".

According to the organisation sexual violence against women is widespread in Kenya - the victims usually suffering in silence.

But the publicity given to Kenyan author Ngugi wa Thiong'o's allegation that his wife was raped last August, has brought the topic more recently into the public arena.