Le Pen infuriates Algeria by draping France with its flag

Poster that targets Islamic extremism also brings cries of plagiarism from Swiss

The French far right leader Jean-Marie Le Pen may be a veteran provocateur but to infuriate both the Algerians and the Swiss with one poster takes genuine talent.

The Algerian government has formally protested to Paris about a poster which associates its flag with Islamisme, or radical forms of Islam. The poster shows France covered by an Algerian flag and a forest of mosque minarets. The slogan reads: "Non à l'Islamisme".

It closely resembles a poster published by a nationalist party in Switzerland before a mosque-building referendum last November. The Swiss advertising agency that devised the original poster said it planned to sue Mr Le Pen's party, the National Front, for plagiarism.

The Algerian government and anti-racist groups in France have more pressing concerns. "We have officially protested," said the Algerian Foreign Minister, Mourad Medelci. "It is up to the French state to take the necessary measures when foreign countries' symbols are dragged through the mud."

Kahled Lasbeur, lawyer for the Movement against Racism, warned of "riots, demonstrations and blood-letting" if the posters are not banned.

The posters have been published by the NF's youth wing and, at first, were mostly displayed in the south of France. They are now appearing on placards, walls and motorway bridges all over the country. The party insists that the posters are a protest against extreme forms of Islam. Opponents say that the use of Algerian flags and minarets is a naked attempt to stir up anti-Islamic and anti-Arab feelings. New legal complaints have been brought by three anti-racism pressure groups.

The veteran far right leader, aged 81, is running to be president of Provence-Côte d'Azur in regional elections, which take place over two rounds this Sunday and the following weekend. If his own past pronouncements are to be believed, this may be Mr Le Pen's last political campaign. He has suggested that he plans to retire, possibly in favour of his daughter Marine Le Pen, 41, before the next national presidential election in 2012. In recent days, however, he has hinted that he might go on "for ever" if he scores well in the regional elections over the next 11 days.

In the most recent opinion polls, Mr Le Pen's list is said to command around 15 per cent of the vote in the Provence region – enough to reach the second round.

Overall, the National Front is given about 8 per cent of the vote nationwide, a substantial slump from its "glory" days in the late 1990s and 2002. Mr Le Pen's advancing age, the party's financial troubles and divisions over the more moderate approach taken by Marine (on some issues) have reduced the National Front's campaigning strength and grassroots membership.

The "Islamiste" posters are an attempt to appeal to the party's core, xenophobic support. Marine Le Pen responded to the attempts to ban the poster yesterday by calling the anti-racist groups "porteurs de valise" or bag-carriers. This is a loaded phrase, which was used to describe French supporters of the Algerian independence movement in the late 1950s and early 1960s but also carried implications of "carriers" of explosives.