The Netherlands has recalled its ambassador to Iran amid accusations Tehran was behind the assassination of dissidents on Dutch soil and had failed to engage with attempts to resolve the issue.
Foreign minister Steg Blok said its diplomatic representative was withdrawn “for consultations” after two Dutch diplomats working in Tehran were expelled over the dispute on Sunday.
Iran's decision was described as "unacceptable" according to Geoffrey van Leeuwen, director of the Dutch foreign ministry's Middle East and North Africa division.
In a letter to the Dutch parliament, Mr Blok said "the deportation of two Dutch diplomats is not acceptable and is negative for the development of the bilateral relationship".
“This decision follows the announcement by the Iranian Ministry of Foreign Affairs that two Dutch diplomats at the embassy in Tehran have been declared persona non grata and have to leave the country.”
Iran's ambassador to the Netherlands has also been summoned.
The incident is just the latest evidence of a the deterioration in Iran-Netherlands relations, stemming from the allegations Tehran is behind the assassinations of dissidents in Europe.
In January Mr Blok said there were “strong indications” Iran was involved in the "liquidation" of two Dutch citizens of Iranian origin in 2015 and 2017. The Netherlands last year expelled two Iranian diplomats over their alleged links to the plots.
"The Netherlands considers it probable that Iran had a hand in the preparation or commissioning of assassinations and attacks on EU territory," Mr Blok said in a letter earlier this year to the Dutch parliament.
The European Union imposed sanctions in January that targeted Iran's intelligence services following a number of supposed assassination plots linked to Tehran on European soil in 2017.
Mr Blok said at the time: "The Netherlands considers it probable that Iran had a hand in the preparation or commissioning of assassinations and attacks on EU territory."
The two men who the Dutch believe Iran helped kill were Ali Motamed, 56, who died in Almere in 2015, and Ahmad Molla Nissi, 52, killed in The Hague in 2017.
Motamed, also known as Mohammad Reza Kolahi Samadi, had been sentenced to death in Iran in absentia in 1981 for his alleged role in a bombing that killed 73 - including including Chief Justice Ayatollah Mohammad Beheshti, who was described as the second most powerful man in Iran after Supreme Leader Ruhollah Khomeini.
In exile, Motamed had been working under an alias as an engineer. He lived with his wife and son in the Netherlands until he was shot in the head at point blank range.
In 2018, French police foiled a plan to a bomb an Iranian opposition rally in Paris. A man arrested in connection with the plot, Assadollah Assadi, worked at Tehran's Ministry of Intelligence and Security in Vienna, and is currently in custody in Belgium.
Three others are also detained over the incident, including a couple caught with half-a-kilogram of powerful explosives.
Another Iranian, Saeid Hashemi Moghadam, deputy minister and director general of intelligence, was placed on an EU terror list at the time.
Dutch politicians expressed outrage that Iran was defying its requests for investigations and prosecution of those responsible. "Iran must stay away from our people," said Sven Koopmans of the VVD paty. "Diplomacy also means to be clear where the boundary lies."
There were calls for the Iranian ambassador in The Hague to sent home. "The Iranian ambassador must be declared persona non grata and immediately expelled," said Raymond De Roon of the PVV.
"The world is turned upside down,” added Sjoerd Sjoerdsma of D66 party. "Iran is involved in liquidations on Dutch soil, but instead of participating in the criminal proceedings, Tehran expels Dutch diplomats."
Last October, neighbouring Denmark recalled its ambassador to Tehran and requested EU assistance after it accused Iran of being behind an attempted assassination of a dissident on Danish soil.
Police were forced to close of access to the capital Copenhagen from the rest of the country after a suspicious car was reportedly spotted near the home of a well-known Iranian opposition figure.
Iran denies the accusations.
Europe as a whole has taken a softer stance against the Iranian regime, at least in comparison to the currently Donald Trump-run US administration. It has sought to circumvent US sanctions on Iran and continue trade.
This however, could change if Iran does not stop its apparent assassination campaign against dissidents one analyst has previously said.
"Iran-orchestrated assassination and bombing plots over the past year against opposition groups in France, Denmark, and the Netherlands have arguably helped narrow the rift between the US and the EU," wrote analyst Maysam Behravesh in the American Conservative.