The passenger jet was shot down over eastern Ukraine on July 17, 2014 en route from Amsterdam to Kuala Lumpur killing all 298 on board.
"We are considering speaking to authorities about another search for human remains," Evert van Zijtveld, chairman of the MH17 victims' foundation, said on Saturday.
"As relatives, we simply don't want any human remains to be left behind," Van Zijtveld, who lost a son, daughter and his parents-in-law, told AFP.
The Malaysia Airlines Boeing 777 passenger jet was shot down over eastern Ukraine on July 17, 2014 en route from Amsterdam to Kuala Lumpur killing all 298 on board, most of them Dutch citizens.
Last Sunday, when freelance journalist Michel Spekkers returned to Amsterdam from Ukraine, Dutch police confiscated the items he had collected including the human bone fragment.
DNA tests this week showed that the bone belonged to one of the victims, whose other remains were identified in 2014, Dutch prosecutors said in a statement Friday. The victim's family was informed.
The rest of the articles brought back by Spekkers were "not relevant to the criminal investigation," prosecutors said.
A Dutch-led criminal investigation into the attack concluded in September that a BUK missile, transported from Russia, was fired from a field in a part of war-torn Ukraine then controlled by pro-Russian rebels, and hit the plane. But it stopped short of saying who pulled the trigger.
Van Zijtveld said the new findings had opened painful wounds for victims' relatives, who now wanted to know why a journalist was able to find the human remains.
He earlier told the NOS public broadcaster that Spekkers did not find the bone in a isolated area but at a shed where a search team had brought together all items found from the crash site.
"If it turns out that not all commitments to return human remains have been heeded, we'll consider discussing the possibility of another mission go and bring back our loved ones," Van Zijtveld said.