A major police operation took place on Monday evening in the European Quarter of Brussels.

Belgian police have arrested two suspects after gunmen interrupted a sale of secondhand luxury watches in an underground carpark near the Brussels headquarters of the European Union, prosecutors said Tuesday.

Late on Monday, heavily armed police flooded a residential street in the Belgian capital's European Quarter, with a helicopter overhead, just days before the area is to host a summit of the 27 EU leaders.

According to initial information, a group was selling luxury watches in an underground parking space when a violent incident erupted.

According to the prosecutor's office, "two people were said to have been assaulted and held against their will... a gun is said to have been used".

After the assault, two suspects fled the scene and the alleged victims were able to escape and alert neighbours who called the police.

Officers sealed off an address in a street fewer than 500 metres (yards) from the headquarters of the European Union's main institutions for at least five hours.

The next day, investigators said two men aged 33 and 39 had been arrested and an investigation opened after a police complaint that two people had been assaulted and held against their will.

"The investigation continues," the prosecutors' office said.

On Thursday, the 27 EU leaders are due to meet at the European Council for their latest summit.