The French government will defy official advice and put forward a draft law next month to ban the burka, or full-body veil, from all public places.

Despite warnings that such a law would be open to constitutional challenge, President Nicolas Sarkozy insisted yesterday that a ban on the burka was needed to protect the “dignity of women”.

The debate on the law, to be completed by July, will scramble the normal political boundaries between right and left. It will also divide France's Muslims.

Although the full-length veil is worn by only 2,000 women in France, its gradually increasing presence is seen by politicians on both the right and left as an affront to the official republican values of liberty and equality. Other politicians, on both right and left, say that a law is unnecessary, probably unconstitutional and likely to embitter relations.

Mainstream Muslim organisations say that a ban could make even moderate Muslims feel that their religion is resented in France. On the other hand, the proposed ban was heartily welcomed yesterday by a radical group which defends women's rights in France's troubled, multi-racial suburbs.

Sihem Habchi, president of Ni Putes, Ni Soumises (“neither whores, nor submissive women”) said the law would be a “victory for women” and would “turn a new page of emancipation for those women who are confronted daily with a choice between imprisonment (in the burqa) and social death”.

Last month the Conseil d'Etat, the watchdog on the legality of actions by the state, warned that a complete ban on the burka from French streets was unworkable and probably unconstitutional.

The council, made up of senior public figures, suggested that it would be more sensible to ban the full-length veil from public buildings, such as schools, hospitals, town halls and government offices.

The French State Ombudsman, or Médiateur de la République, Jean-Paul Delevoye, also denounced the idea of a complete legal ban yesterday. “I revere the law but I don't like total bans,” said Mr Delevoye, a centre-right politician from the same party as President Sarkozy.

“What are we going to do about the Saudi women who like to come and spend money on the Champs Elysée?”

Government spokesman Luc Chatel said that President Sarkozy and the cabinet had considered the argument for a partial ban but had rejected it. “The dignity of women is not something you can divide into pieces,” Mr Chatel said.

The debate was sparked last summer by a member of parliament. It was seized upon by President Sarkozy, who insisted that the wearing of a full-length veil “has no place in France”.