By Jonathan Kent BBC correspondent in Kuala Lumpur

Anwar says his back problems stem from a prison beating

Anwar was rushed from prison to hospital on Tuesday evening after his condition deteriorated.

But his supporters and the government are at loggerheads over whether he should be treated in Malaysia or abroad.

Anwar is serving a nine-year jail term for sodomy.

For years Anwar has made his public appearances in a wheelchair.

He says he suffered a back injury as a result of being beaten by police after his arrest in September 1998.

According to his lawyer, Sankara Nair, that injury has gone untreated and has now led to a narrowing of his spinal canal, the swelling of a kidney and nerve damage - with the result that Mr Anwar is losing the feeling in one of his legs.

Though he is not paralysed yet, "he's slowly but surely getting there," Mr Nair said.

Mr Anwar has long insisted he receive treatment from specialist surgeons in Germany.

Wrangling

The government does not want him to leave the country because he is still serving a nine-year jail term for sodomy.

But Mr Anwar's family dispute the government's assertion that Malaysian medical facilities are more than adequate to treat him.

Mr Anwar's political fortunes have waned since he fell out with his mentor, the former Prime Minister Dr Mahathir Mohamad.

In the years that followed his arrest and jailing, thousands regularly took to the streets to protest at his treatment, and he is still regarded as a political prisoner by some governments, including that of the United States.