The nun was reportedly assaulted on Aug 25, days after the murder of a Hindu priest sparked the violence in Orissa's Kandhamal district.

'Four people have been arrested in connection with this shameful act,' Orissa Chief Minister Naveen Patnaik told reporters.

Separately, Kandhamal superintendent of police Praveen Kumar told the Press Trust of India that the 'woman was medically examined and the report received by us suggests the possibility of rape.'

The arrests followed reports of fresh clashes and arson late on Thursday in Boudh district adjoining Kandhamal.

'We have sent fresh security reinforcements to Kandhamal and Boudh districts,? Orissa police chief Manmohan Praharaj said.

Officials on Friday said the death toll in the clashes had risen to 33 with one more death overnight.

The attacks on churches, prayer halls and Catholic-run schools began after the murder of a revered Hindu holy man, Swami Laxamananda Saraswati, and four of his followers on Aug 23. The killings remain unsolved.

At the root of the violence are long-standing accusations by hardline Hindus that missionaries bribe poor tribals and low-caste Hindus to convert to Christianity by offering free education and health care.

The Hindu holy man had been associated with a radical group opposed to Hindus converting to Christianity.

The attacks have been condemned by the Vatican and the European Union and described as 'a national shame' by Indian premier Manmohan Singh.

Christians account for 2.3 per cent of India's billion-plus Hindu majority population. -- AFP