Taking the tablets in the province is against the law – unless a woman’s life is at risk or there is a permanent or serious risk to her mental or physical health.
Sky’s Ireland correspondent, Darren McCaffrey, said there was a large police presence at the hour-long demonstration between Belfast’s crown and high courts.
“A woman can be sentenced to life in prison if they commit abortion here even in cases of fatal foetal abnormality, rape or incest,” McCaffrey added.
One of the demonstrators, Eleanor Crossey Malone, said she took action “in defiance of the extremely outdated, medieval, anti-choice laws that exist in Northern Ireland”.
“We are not willing to accept it any more,” she said.
One woman who openly took a tablet was led away for questioning, but campaigners gathered round, insisting she could not be arrested.
After several minutes, officers gave up and left the area.
Ms Crossey Malone, from socialist feminist movement Rosa, added: “Women every day in Northern Ireland are using these pills – as long as we don’t talk about it, as long as we act like it is a secret, politicians are not under pressure to legislate on this.”
Following chaotic scenes, including counter-demonstrations from anti-abortion activists, the protesters headed for Lisburn.
Abortion has become a topical subject in Northern Ireland since the Republic voted to legalise abortion.
Theresa May has since come under pressure to back fresh legislation on the strict abortion laws in the province.
Ireland Prime Minister Leo Varadkar has said women from Northern Ireland could have abortions in the Republic once new laws are introduced there.
Northern Irish people can already access healthcare across the border.
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The new legislation is unlikely to be implemented until the new year, Mr Varadkar has said, adding that the Dail may have to sit longer than expected into the summer to help get it through.
“It’s important that we’ve to act with haste but not so much haste that we put through bad legislation,” he said.