Customs officials have boarded a ship operated by a Dutch abortion rights group to search for abortion pills that are illegal in Poland.
The boat arrived on Sunday without receiving permission to dock
However, a spokeswoman for state prosecutors, Malgorzata Wilkosz-Sliwa, said the Langenort's crew would not be in breach of Polish abortion laws so long as any pills remained on the ship.
"If no-one tries to distribute [the pills], then there is no crime," she said.
Crew member Jeanette Kruseman admits RU-486 pills are on board, but under a seal that will not be broken while the ship remains in Poland.
All our services will be in international waters, whatever they may be
Jeanette Kruseman, Women on Waves
The ship arrived at the Baltic Sea port of Wladyslawowo on Sunday where it was met with fierce protests in a country that has one of Europe's toughest anti-abortion laws.
In Poland, pregnancy can be terminated only if it threatens the woman's health, the foetus is irreparably damaged or if the pregnancy results from rape or incest.
The ship is crewed by members of the Dutch Women on Waves group who say they plan to offer Polish women advice on contraceptives.
The group has previously offered RU-486 to women after leaving nations with strict anti-abortion laws for international waters.
"All our services will be in international waters, whatever they may be," she said.
People performing or helping with an abortion in other circumstances in Poland can face up to three years in prison.
The ship's visit angered Poland's influential Roman Catholic church and anti-abortion groups that have asked prosecutors to investigate if it violates Poland's law.
In 2001, Women on Waves took another boat to predominantly Roman Catholic Ireland, but called off plans to offer RU-486 following last-minute legal and logistical complications.