Some 20,000 protesters gathered outside Brussels' Nord (North) Station as COP28 talks are underway in Dubai, Anadolu Agency reported.
The crowd marched towards Cinquantenaire Park, passing through Schuman Square, where European institutions are located.
Protesters carried signs, some of them reading, "Climate crisis is human rights crisis," "Break free from fossil fuels," and "Policy change not climate change."
People with Palestinian flags were also among the protesters during the rally as Israel continues its attacks on the Gaza Strip.
Heads of state and government worldwide, as well as civil society and businesses, are gathering in the United Arab Emirates at this year's UN climate change conference to accelerate action to tackle the climate crisis.
Talks will continue until Dec. 12.