Russian-based professional trolls sent more than 900 tweets in Dutch over two years – but they had almost no impact on public debate, according to an investigation by NRC.

The newspaper said it had studied more than 200,000 tweets sent from the Internet Research Agency in St Petersburg, the ‘troll factory’ said to have influenced the Brexit vote in the UK and the election of Donald Trump as US president.

In the Netherlands, troll accounts were mainly active in discussions about Islam and immigration. The co-ordinated bombings carried out by Islamist terrorists at Brussels Airport in March 2006 sparked a series of tweets in Dutch using English hashtags such as #IslamIsTheProblem and #IslamKills.

Six of the accounts sent an identical tweet ‘Pfff dit vindt ik verschrikkelijk’, containing the same grammatical error (a so-called ‘dt-fout’ in the verb form), over the space of several hours.

Troll accounts focused their attention on the Netherlands, mainly by retweeting comments by alt-right cheerleaders such as journalist Wierd Duk and conspiracy theorist Joost Niemöller. One account, going by the name of @Ten_gop, retweeted 32 messages by PVV leader Geert Wilders in four months.

Ironically, the fake accounts had more success in the Netherlands with tweets in English. More than 6,000 Dutch troll accounts shared 30,000 English-language messages with a total of 9.5 million followers.

Fake followers

In a separate development, some of the Netherlands’ highest-profile politicians saw their follower count slashed after Twitter removed millions of fake accounts from its system.

Geert Wilders lost around 15% of his nearly 1 million followers following the clear-out. The two MPs from the Denk party, Tunahan Kuzu and Farid Azarkan, had their numbers slashed by 34% and 39% respectively from a much smaller base.

Twitter said around 6 per cent of all accounts had been culled in the operation, designed to improve the website’s credibility.