The European Parliament has taken an unusual step to crack down on racism and hate speech in its own house. Representatives have granted special powers to the president to axe live broadcasts of parliamentary debate in cases of racist speech or acts, and the ability to purge any offending video or audio material afterwards.

However, the rules on what is considered offensive are not clear and concerns have been raised about manipulation and censorship.

"This undermines the reliability of the Parliament's archives at a moment where the suspicion of 'fake news' and manipulation threatens the credibility of the media and the politicians," said Tom Weingaertner, president of the International Press Association.

After Britain's decision to leave the European Union, the rising popularity of anti-immigrant candidates such as Geert Wilders in the Netherlands or far-right Marine Le Pen in France is worrying Europe's political mainstream.

At the European Parliament, where elections are due in 2019, many say the need for action against hate speech and strong sanctions for offenders is overdue.

The assembly - with two seats, in the Belgian capital of Brussels and Strasbourg in France - is often the stage for political and sometimes nationalist theatre.

Beyond routine shouting matches, members occasionally wear T-shirts with slogans or unfurl banners. Flags adorn some members' desks.

"There have been a growing number of cases of politicians saying things that are beyond the pale of normal parliamentary discussion and debate," said British MEP Richard Corbett, who chaperoned the new rule through the assembly.

"What if this becames not isolated incidents, but specific, where people could say: 'Hey, this is a fantastic platform. It's broad, it's live-streamed. It can be recorded and repeated. Let's use it for something more vociferous, more spectacular'," he said.

The new rule procedure allows the chair of debates to halt the live broadcast "in the case of defamatory, racist or xenophobic language or behavior by a member".

The maximum fine for offenders would be around €9000 (£7600).

Under the rule, offending material could be "deleted from the audiovisual record of proceedings".

That means citizens would never know about it unless reporters were in the room. Weingaertner said the IPA was not consulted on that.

A technical note outlines a procedure for manually cutting off the video feed, stopping transmission on in-house TV monitors and breaking the satellite link to halt broadcast to the outside world.

A tape in four languages would be kept running to serve as a legal record during the blackout. A more effective and permanent system was being sought.

It is also technically possible to introduce a time delay so broadcasts appear a few seconds later. This means they could be interrupted before offending material is aired.

But the system is unwieldy. Members have the right to speak in any of the European Union's 24 official languages. An offending act could be over before the assembly's president Antonio Tajani has a chance to hit the kill switch. Misunderstandings and abuses could crop up.

Even those involved in the move acknowledge it is a sensitive issue.

Helmut Scholz, from Germany's left-wing Die Linke party, said EU lawmakers are elected - indeed the EU parliament is the bloc's only popularly elected institution - and must be able to express their views about how Europe should work.

Nazi rallying cries and racist obscenities are relatively rare but not unheard of.

"We need an instrument against that, to take it out of the record, to stop distribution of such slogans, such ideas," Scholz said.