KUALA LUMPUR, Sept 22 (Reuters) - The wife of arrested Malaysian ex-finance minister Anwar Ibrahim was under investigation for sedition on Tuesday because she had suggested her husband might be injected with the AIDS virus to prove allegations of sodomy against him, police said.

A police spokesman said the comments of Anwar's wife, Wan Azizah Wan Ismail, ''contained seditious elements which could cause hatred towards the administration of justice in Malaysia.''

Anwar was arrested on Sunday night under Malaysia's Internal Security Act, which authorises indefinite detention without trial.

He had previously been accused of treason and sexual crimes, and he was arrested the day after a court found his adopted brother and an Anwar speech writer guilty of committing sodomy with the sacked finance minister.

Anwar, who has denied the assertion of sodomy, said the accusations against him were part of a political conspiracy inspired by Prime Minister Mahathir Mohamad to head off a challenge to his leadership.

''We have news to say that maybe Anwar's life is in danger because he may be given some injection of the HIV virus to prove whatever the allegations are, and course in the long run to cost him his life. This is why I'm afraid of my husband's life,'' Wan Azizah said in television interviews on Monday night.

Malaysia's official Bernama news agency said police were investigating the comments.

''Federal police headquarters public relations head Superintendent Ghazali Mohd Amin said police seriously viewed her statement as it contained seditious elements which could cause hatred towards the administration of justice in Malaysia,'' Bernama said.

Wan Azizah has become a rallying point for the opposition since her husband's arrest and had been visited by police twice in the 24 hours to 0600 GMT Tuesday.

She said police had advised her not to make anymore "dramas'' because it was disruptive to the country.