Brussels (AFP) - The organisers of a "March Against Fear" planned for Sunday to mark the Brussels terror attacks said they had cancelled the event after the authorities asked them to do so because of security fears.

"We understand this request. The security of our citizens is an absolute priority. We join the authorities in proposing a delay and ask people not to come this Sunday," the organisers said in a statement on Saturday.

The authorities earlier asked for the march to be put off, perhaps for several weeks, to allow the police to concentrate their resources on the investigation into the attacks which left 31 dead and 300 wounded.

"We invite the citizens tomorrow to not have this manifestation," Interior Minister Jan Jambon said, speaking in English.

In an earlier statement, the organisers said the march planned for Sunday was meant to show that Brussels and the country at large refused to be intimidated by terrorism and that everyone stood together.

"This week, we, Belgian citizens have been attacked, in how we live, our customs, our rights, our liberty," they said.

"The first reaction in such events is to withdraw but on reflection, fear must give way to hope and the defence of our values."

The march was due to begin at 2:00 pm (1300 GMT) at the central Place de La Bourse which, carpeted with flowers and tributes, has turned into a shrine to the victims.

Brussels mayor Yvan Mayeur said he recognised and shared the feelings of those who wanted to participate but given the absolute need for the police to focus on the attacks, it was best to delay the march.

"Let us allow the security services to do their work and that the march, which we too want to take part in, be delayed for several weeks," Mayeur told a press conference with Jambon at the national crisis centre.