A major evacuation was launched at the European Parliament after a man dressed in camouflage was arrested, and a chainsaw and gun found in his car.
Prosecutors in Brussels said the man, from Slovakia, told police officers at the scene that he wanted to meet the European president.
The incident sparked a security scare, including the evacuation of a number of offices nearby. A judge will decide tomorrow whether he faces charges.
It comes as Belgium was put on high alert after security forces foiled a plot by Islamist radicals to attack police stations across the country. Extra soldiers have been deployed.
The former US defence contractor turned whistleblower Edward Snowden has been nominated for a prestigious human rights award.
Snowden is among seven nominees for the Sakharov Prize for freedom of thought, whose past winners include Nelson Mandela and Myanmar opposition leader Aung San Suu Kyi.
Other nominees include the Pakistani education campaigner Malala Yousafzai and Russian former oil tycoon Mikhail Khodorkovsky.
The winner will be chosen by members of the European Parliament on 10 October.
Former Belgian prime minister and Liberal Democrat leader in the European Parliament Guy Verhofstadt has accused David Cameron of "playing with fire" over Europe: