Turkey's leader, meanwhile, demanded to know why one of the victims — a founder of a Kurdish rebel group — had been granted asylum in France.
Crowds of Kurds streamed to Paris from throughout Europe, marching through the neighborhood where Sakine Cansiz's body was found inside a Kurdish information center along with two other activists. Cansiz was a founder of the Kurdish rebel group that has been battling the Turkish government for three decades.
Kurdish activists have demanded that Turkey help investigate who carried out the killings.
Turkish officials have suggested the killings may have been part of an internal feud among Kurdish activists or an attempt to derail Turkey's peace talks with the jailed leader of the Kurdistan Workers' Party. It is known as the PKK and is considered a terrorist organization by Turkey and its U.S. and European allies.
"We are all PKK," the crowd chanted in Paris, raising Kurdish flags and giant banners plastered with photos of the three women.
The deaths have put France in a difficult position as it tries to improve ties with Turkey. Turkey frequently accuses France and other European nations of not cooperating in its struggle against the rebel group, and notably of failing to extradite wanted militants.
Cansiz received asylum from France in 1998, according to Devris Cimen, head of the Frankfurt-based Kurdish Center for Public Information. At the same time, according to a WikiLeaks cable, she and another PKK member were considered key fundraisers for the rebel group in Europe.
Turkish Prime Minister Recep Tayyip Erdogan said Saturday that Cansiz was arrested in Germany in 2007, then freed despite a Turkish extradition request. Turkey notified France as recently as Nov. 5 that Cansiz was in Paris, but France took no action, he said.
French President Francois Hollande has said he and several other politicians knew one of the women professionally. He did not say which one.
"How can one regularly meet with a person or persons who are a member of an organization that has been declared a terror organization by the European Union and are wanted by a warrant?" said Erdogan. "What kind of a policy is this?"
France must "immediately shed light (on the crime), find the culprits and leave no question marks," Erdogan said.
The Kurdish crowd in Paris had similar demands, calling for justice from France.
Aylin Erten, 18, a high school student, said she came to Paris from her hometown of Strasbourg.
"As a Kurd, I feel concerned because these three women were symbols of our community and this crime didn't happen in Turkey .... it happened in France, in Paris," she said.
Nazmi Gur, a Kurdish legislator who accompanied Kurdish leaders to Paris from Turkey, said the bodies of the three women will be returned to Turkey soon.