The protest ended near the heavily-guarded home of Jaroslaw Kaczynski, leader of Poland's ruling party Law and Justice (PiS), which authored the new law.
The law, which forbids abortion on foetal damage grounds, practically introduces a near complete ban on abortion. Pregnancy terminations will now be permitted only in cases of rape, incest, or danger to the mother's health or life. Doctors performing abortions illegally will face prison sentences.
The protests began earlier in the day in downtown Warsaw, the demo reached the vicinity of Kaczynski's residence around 11:00 pm.
Warsaw police have said that six people have been detained and two policemen hospitalised in result of tussles between protesters and police.
Thousands of people marched through other cities across Poland on Friday to protest against the new abortion law. (PAP)
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