Dutch Prime Minister Mark Rutte on Thursday lashed out at his Slovenian counterpart over a "tasteless" tweet invoking a baseless conspiracy theory and summoned Slovenia's ambassador to complain.

Slovenia's right-wing Prime Minister Janez Jansa, whose country holds the six-month rotating EU presidency, posted a picture on Twitter calling several Dutch MEPs "puppets" of financier George Soros, including a recently deceased ally of Rutte's.

"Tasteless tweet by Janez Jansa (@JJansaSDS) about MEPs. I condemn it in the strongest possible terms," tweeted Rutte, who has had a series of run-ins withcentral European leaders.

"The government just conveyed this same sentiment to the Slovenian ambassador in The Hague."

The offending tweet by Jansa came as a European Parliament delegation featuring prominent Dutch member Sophie in 't Veld visited Slovenia to look at concerns over media freedom and the rule of law.

Jansa's picture of a chart linking Soros -- a hate figure for European far-right and anti-Semitic conspiracy theorists -- to MEPs also included Hans van Baalen, a member of Rutte's VVD party who died in April aged 60.

The Jansa tweet later appeared to have been deleted.

But Jansa later fired back an unrepentant salvo at the Dutch PM in which he referenced the murder in Amsterdam in July of Peter R. De Vries, a top crime reporter in the Netherlands.

"Well, Mark, @MinPres, don't waste time with ambassadors and media freedom in Slovenia. Together with @SophieintVeld, protect your journalists from being killed on the streets," said Jansa.

The row is the latest in a series of confrontations that the plain-speaking Rutte has had with right-wing and authoritarian leaders in central Europe in recent months.

The Dutch prime minister has frequently clashed with Hungary's Viktor Orban -- like Jansa, another Soros critic -- on subjects including an EU coronavirus rescue package and a Hungarian LGBT law.

Rutte, leader of one of the EU's biggest net contributing countries, has also run up against countries such as Poland and Hungary over his insistence that recovery funds for poorer countries should be linked to the rule of law.