Smartly dressed armed robbers staged a brazen daylight raid on an international art fair in the Dutch city of Maastricht Tuesday, using a sledgehammer to smash their way into a jewellery display case.

Police said they had arrested two of the four suspects and were hunting the others after a robbery which led to terrified visitors being evacuated from the European Fine Art Fair (TEFAF) in the southern city.

Dramatic images on social media showed the suspects wearing flat caps, glasses and jackets threatening visitors with what appeared to be handguns during the heist, before running off.

"No one was injured and the robbers took possession of property," Limburg province police said in a statement.

Police closed off nearby roads and a major road tunnel to hunt for the suspects immediately afterwards, they said.

"The police investigation, which started immediately after the robbery, led to two arrests... The police investigation is continuing in full swing. The focus is on tracing the suspects."

Dutch media said the display case targeted by the robbers contained diamond jewellery and other items from London jeweller Symbolic and Chase.

The firm was not immediately available for comment.

TEFAF is one of the biggest art fairs in Europe and regularly draws tens of thousands of visitors.

- 'Disarm offender' -

"The fair’s security teams worked quickly to disarm an offender and Dutch police were on site within minutes. Nobody was injured during the incident," a TEFAF spokesperson told AFP in an emailed statement.

The fair had "robust procedures in the event of a security breach", it said.

"These were precisely followed and all visitors, exhibitors and staff were safely evacuated. The fair has now reopened," it added.

The fair and the MECC conference centre where it is being held were "working with the authorities" and would not comment further, it said.

Videos on social media showed the four men amid scenes of chaos at the art fair.

One smashed his way into a jewellery case with a sledgehammer, striking what appeared to be armoured glass at least 12 times while burglar alarms wailed.

Two of the men brandished what appeared to be weapons at a bystander, who tried to intervene using a large glass vase full of flowers before backing off.

The hammer-wielding suspect finally smashed through the glass, reaching in to pick up something before putting it into a bag.

The men then ran off past a bemused elderly man, who had sat nearby on a bench throughout the drama.

- 'Still shaking' -

Pictures on social media showed a shattered glass case at the exhibition.

One visitor, Jos Stassen, told Dutch public broadcaster NOS that he had gone to the exhibition on Tuesday to look at the art in peace.

"Normally it is very quiet ... serene. But now I suddenly heard a lot of noise and I turn around and suddenly saw those men," NOS quoted him as saying.

"One started beating and the others kept people away, scared everyone. I also saw a weapon. It went very fast and it lasted a very short time but I'm still shaking a little bit."

The phrase "Peaky Blinders" began trending on social media in the Netherlands following the raid because the caps worn by the suspects resemble those in a British historical crime drama of the same name.

The fair has been running for more than 30 years and was returning this year after a break due to the Covid pandemic.

TEFAF features hundreds of works, including one 17th-century drawing by a Dutch Old Master on sale for one million euros.

It is not the first time the fair has been targeted by criminals.

A ring and a diamond necklace worth 860,000 euros ($1.2 million at the time) belonging to a London jeweller were stolen at the exhibition in 2011.