Foreign nationals were negatively typecast in the campaign ahead of this year's parliamentary elections, the Federal Commission against Racism reported on Tuesday.
At a news conference in the capital, Bern, it presented a study pointing the finger of blame in particular at the rightwing Swiss People's Party, which made large gains in October's vote.
The commission called on politicians to prevent such "discriminating portrayals" in the future.
The study, compiled by Zurich University's Research Department on Public Opinion and Society, found that Muslims and young foreigners were particularly targeted.
University researchers looked at the typecasting of foreign nationals in seven daily Swiss newspapers, four Sunday titles, two weeklies, and the main television news programmes in the German, French and Italian regions of the country.
They found that the People's Party propagated three quarters of the negative portrayals.
In a statement, the commission said the party's strategy and the reactions of the media and others ensured that negative stereotypes shaped the electoral campaign to a large extent – even more than did environmental issues.
Criticism of this negative image of the foreign population was significantly greater in French-speaking Switzerland.
"During the campaign we experienced a black-white debate," commented the commission's vice-president Boël Sambuc.
In parallel with the political populism, a media populism had emerged. The media preferred to simplify rather than analyse, she said.
The commission said the study had revealed how the "popular right" made use of the image of foreigners "to foment existing xenophobic sentiments".
The People's Party was unavailable for comment on Tuesday.
No balanced image
The statement added there were "other actors", including the media, who were not in a position to formulate a balanced image of the immigrant population.
If foreign nationals are portrayed in the media either as criminals or as victims of racism, it is difficult to see them as neighbours, workers or colleagues, the commission said.
In their findings, the researchers noted that the People's Party in particular made heavy use of forms of typecasting which generated distance between foreign nationals and ethnic minorities, and the rest of the population.
Since large sections of the media and politicians, for example from the centre-left Social Democratic Party – responded, such labels were corrected but became a feature of reporting as a result.
The study also found that some of the negative depictions of foreigners were left unchallenged, "meaning that the association of foreign nationals and ethnic minorities with certain negative subject contexts was barely corrected".
Generally speaking a highly contrasting image was produced in which foreign nationals and ethnic minorities were portrayed either as perpetrators or victims, the authors said.
swissinfo with agencies
The basis for the study came from articles and reports in seven daily newspapers (Berner Zeitung, Blick, Le Matin, Le Temps, Neue Luzerner Zeitung, Neue Zürcher Zeitung, Tages-Anzeiger), four Sunday newspapers (Le Matin Dimanche, NZZ am Sonntag, Sonntags-Blick, SonntagsZeitung), two weekly newspapers (Weltwoche, Die Wochenzeitung) and the main television news programmes of Swiss television.
The People's Party ran a poster campaign in the election run-up depicting white sheep kicking a black sheep off a Swiss flag. It drew worldwide media attention and criticism from the United Nations.
Study's main findings
The "foreigner problem" was the key topic of the parliamentary election campaign, even ahead of environment policy
Explicit typecasting came mainly from the Swiss People's Party (73%). It made the issue of foreigners a key component of its election campaign through election advertising it financed or through the echo of corresponding reports in the mass media.
A long way behind the People's Party, a number of newspapers formed the second group of players using negative typecasting (7%). These included the NZZ am Sonntag (2%)and the Weltwoche (1%).
"Only very occasionally" did representatives of the centre-right Christian Democrats and Social Democrats expressed negative typecasting of foreign nationals and ethnic minorities.
The People's Party placed "by far the highest" number of adverts in the press (29% of all advertisements assessed).