The PES move is largely seen as a response to the recent formation of a Dutch minority government which has the implicit backing of Geert Wilders' right-wing populist party PVV.
The PVV does not participate in the cabinet, but the liberal-conservative coalition led by Prime Minister Mark Rutte has a written agreement with the party which guarantees it a say in policy formulation.
Announcing his cooperation pact with the new government this month, Wilders said Rutte's cabinet would introduce a burqa ban and cut immigration by half.
According to the Socialists, recent statements by so-called mainstream politicians are sending a dangerous and insidious signal that such extreme views are acceptable.
Recent comments by French centre-right politicians on the Roma question, by Italian leaders who have come to their aid, by German regional leaders on the very idea of immigration and the acceptance of extremist support for a ruling coalition in the Netherlands have only exacerbated the situation, the statement reads.
Referring to recent events in the Netherlands, PES President Poul Nyrup Rasmussen said that unfortunately, some "mixed signals" had caused concern in recent months.
"We hope that this PES 'code of conduct' will act as a spur for other European parties to act in a principled way," he added.
Socialists no saints either
However, Socialists cannot claim to be immune to racism or xenophobia. Thilo Sarrazin, a Social Democrat politician and board member of the German Federal Bank, published last August a book in which he deplored the lack of intellectual performance by some ethnic groups in Germany and Muslims in particular.
The centre-left SDP party is now trying to get Sarrazin expelled. He has already lost his job at the Federal bank.
Even worse, in Slovakia, the former government of Robert Fico, the leader of SMER, a socialist-affiliated party, was in coalition with extremist party SNS of Jn Slota, the latter being known for his inflammatory anti-gipsy and anti-Hungarian rhetoric. Fico's SMER is now in opposition.
The PES calls for condemnation of all racist, xenophobic, discriminatory or nationalistic statements or actions and warns against joining ruling coalitions or electoral alliances with parties that incite ethnic prejudices and racial hatred at European or national level.
It also calls on mainstream parties to refuse support from such parties to form a government, preventing another Netherlands-like scenario.
Furthermore, the PES fights against legitimising the discourses of such parties by refusing to engage in their terms of the debate and not taking up their ideas in its political platforms or in the policies it implements when in government.
This more general appeal could be seen as a reproach of recent policies by the French authorities to expel Roma to their native Bulgaria and Romania.
The PES also calls for the isolation of members of mainstream parties who do not respect these principles.
Sources contacted by EurActiv gave different interpretations of the PES statement. One said that it would be wrong to see it as anything more than an attempt to make their centre-right opponents feel uncomfortable.
But another knowledgeable source said the Socialists feared a scenario in which the centre-right party of a major EU country would enter into a coalition with a far-right force. Such a move would at first constitute a shock, but then open the door for similar alliances in many EU countries and change the face of Europe, the source said.