Mr Kaalep admitted on Wednesday that he had posted social media comments under fake accounts and even had two opinion piece articles published in daily Eesti Päevaleht (EPL) under the pseudonym ''Bert Valter''.

Mr Kaalep's defence was in the main two-fold, first that the practice of using a nom de plume had a long pedigree, and second that in the current prevailing ''liberal'' climate, many people were afraid to express their opinion openly for fear of repercussions and so the practice was a necessary safeguard for freedom of speech. However, he added that he himself was unafraid to make public statements openly.

''Using a nom de plume in artistic expression is acceptable practice,'' said Mr Tammerk.

''However, if an attempt is made to influence public opinion under a pseudonym, this cannot be justified on the grounds of 'freedom of expression'. It is in fact public deception,'' Mr Tammerk went on.

Not a literary pursuit

He also noted the distinction between humorous pseudonyms, and those aimed at giving the impression that the author was a genuine person, both in online comments trolling, and other areas.

''By trolling we mean those who maliciously and systematically attempt to distort public debate under false names,'' Mr Tammerk continued.

''Submitting a contribution to the media under a false name is nothing other than acting dishonestly. It is thus a good thing that [daily] Postimees has drawn attention to some examples. This forces editorial staff to be more cautious when publishing outside contributions. This has in fact been standard practice in many countries, that an editorial office does not publish pieces or even reader letters without being sure that there is a real person behind the contribution. This should be considered in Estonia too,'' Mr Tammerk continued.

As regards journalistically valuable tips, Mr Tammerk said it was clear that principles of source protection should apply.

Postimees says dozens of fake accounts used

''The journalist themselves knows who gave them any tip off leading to an investigatory story, but the source themselves may, if desired, remain anonymous to the public,'' he continued. This is a million miles away from trolling under a fake name or account, including commenting in public media and forums, which constitutes unjustified public manipulation, according to Tammerk.

According to Postimees, dozens of fake accounts and pseudonyms had been used to post on social media commentaries. Mr Kaalep announced to the media that he had written under the pseudonym Bert Valter, following the Postimees piece. The two offending EPL articles have been withdrawn from the publication's website. It is not reported whether all the fake social media accounts were managed by Mr Kaalep or a wider network of individuals.

On Sunday, a comment reportedly appearing under a video posted on a social media account belonging to politician Jaanus Karilaid (Centre), mentioned EKRE and made a purported death threat.

The comment, since removed, referred to Haapsalu mayor Urmas Sukles, who was endorsing Mr Karilaid's candidacy.

''Sukles. Note that if EKRE wins the election, your kind of rats will be summarily shot on the spot,'' the comment, which Mr Sukles said he alerted the police to, had reportedly read.

Several fake social media accounts have been closed down thanks to investigative work carried out by the Propastop anti-fake news blog, mostly linked with the #ESTexitEU hashtag and the still-active Estoners social media group.

EKRE itself has reported defacing of its outdoor election posters, which is being investigated by the police. It also says members have received death threats.

Ruuben Kaalep heads up ''Blue Awakening'', EKRE's youth organisation. He is running in the number two spot in the Tartu City electoral district in the March 2019 election.

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