Belgian police arrested a man who had a chainsaw and gun in his car near the European Parliament Monday, prompting the evacuation from several buildings, prosecutors said.
The 32-year-old Slovakian, dressed in military fatigues, said he wanted to meet European Parliament President Martin Schulz, Belgian media reported.
Police later lifted the bomb alert after finding there were no explosives in the man's car, prosecutors told the Belga news agency.
The three buildings, from which hundreds were evacuated, are used primarily for administrative purposes.
"At no time did he seem aggressive," the prosecutor's office said of the suspect. "His remarks were deemed unclear, a security perimeter was set up as a precaution. Several buildings were evacuated and traffic was diverted."
The man later appeared before a magistrate accused of threatening an attack, possessing a prohibited weapon and having a firearm requiring a permit.
Belgian authorities have deployed troops and extra police around key buildings in Brussels and other cities after an Islamist plot aimed at killing police was foiled last month.
Europe in general has been on high alert following the Charlie Hebdo and Jewish supermarket terror attacks in Paris which killed 17 people in January.
AFP contributed to this report.