Many advocates of abortion rights have rallied across the United States, demanding the rights be restored in states where they have been repealed since a Supreme Court decision last year.

The demonstrations took place on Sunday, with about 500 people marching more than 3.5 kilometers through central Manhattan in New York.

The day marked exactly 50 years since the Supreme Court issued a landmark ruling that proclaimed abortion as a constitutional right.

The top court, which is now dominated by conservative justices, overturned the decision last June, triggering a sharp rift between pro-choice and pro-life camps. The reversal allowed each state to decide whether to restrict abortion.

Twelve states currently ban abortion in principle. Bills to strengthen restrictions on abortion have been submitted to legislatures in at least three states this month alone. Most of those states have Republican governors.

Pro-life supporters held rallies in Washington and elsewhere on Friday to demand tougher restrictions on abortion, with many calling for a nationwide ban.