A Brazilian woman who claimed to have miscarried twins after an alleged attack by neo Nazis in Zurich was not pregnant, Swiss investigators have confirmed.

The 26-year-old lawyer had told police three youths sporting neo Nazi symbols had attacked her in a Zurich railway station and carved the initials of the rightwing Swiss People's Party into her skin, resulting in a miscarriage.

Zurich University forensic medicine chief Walter Bär said on Friday that tests showed the woman had not been pregnant and added that "any experienced forensic doctor would not hesitate to assume that this was a case of self-harm".

The marks on her skin were not serious and could easily have been self-inflicted, he told a news conference.

Swiss and Brazilian newspapers had printed photographs of the cuts on the woman's legs and abdomen.

Details of the alleged attack prompted Brazil to summon the Swiss Ambassador and call for a full inquiry. The French News Agency reported that Foreign Minister Celso Amorim expressed "deep concern" over a "case with an obvious xenophobic motive".

The woman is being treated in hospital.

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