The row began after Mr King said in a post on X, formerly known as Twitter, that he “worked frantically behind the scenes” to help make the release of the Raanans possible.
He said he had been “lobbying non-stop” for the release of the mother and daughter “behind the scenes with an eclectic group of 30+ people that would normally never work together or get along”.
But relatives of the two women later dismissed his claims, saying that Mr King was “lying” and that the family never had anything to do with him.
In a statement to TMZ, they said: “First and foremost, we make it clear that he is lying! Our family does not and did not have anything to do with him, neither directly nor indirectly. Not to him and not to anything he claims to represent.”
The statement added: “Natalie told us that this morning was the first time in her life that she came across Shaun King’s name and his posts, after she finally got a phone call after two horrific weeks in captivity in Gaza, and was looking for what was written about her while she was away.”
However, statements from other family members later confirmed Natalie’s brother Ben had been in contact with Mr King.
In a statement posted on his since-deleted Instagram page, Ben said he had been in contact with the activist because he “knew he had many connections with the Palestinian government”.
He added while he has some political disagreements with Mr King, “we both agree that human life is the most sanctified value on this earth.”
Natalie’s father Uri also confirmed his son had been in contact with Mr King, but distanced the family from the activist.
“We reached out to many people far and wide to bring Natalie and Judith to safety. We are not affiliated with Mr King,” he told The Daily Beast.
“Ben, my son was talking with him without anybody in the family knowing about it until today. Our family in Israel posted this statement denying we knew him, before we learned about Ben talking to him. We have nothing further to say,” he added.
Mr King hit back at accusations that he was lying, posting screenshots of his correspondence with Ben, who he claimed is “a longtime supporter of mine”.
He said Ben first got in touch with him on 9 October for help in finding and rescuing his sister, two days after Hamas terrorists stormed into Israel, killing more than 1,400 people and taking hundreds hostage across the Gaza border.
He added that he and Ben spoke and messaged over a hundred times after that day.
Mr King said that he had recorded all conversations with Ben “for my own protection,” though it is not clear if Ben knew he was being taped.
Screenshots posted by Mr King show he told Ben he was “pushing hard behind the scenes” for the release of the Raanans. He also suggested the family should get an “experienced hostage negotiator on board” to help with the release of Natalie, 17, and her 59-year-old mother.
It is unclear what exact role Mr King played in the release of the hostages.
Mr King later claimed that the family was distancing itself from him because of pressure from “Israelis”.
The Independent has contacted Mr King for further comment.
The release of the American-Israeli mother and daughter came on Friday, two weeks after they were kidnapped and taken into Gaza by Hamas militants.
The two women from Chicago were visiting relatives in Israel at the time.
Their release was orchestrated by the Qatari government, in coordination with the International Committee of the Red Cross, the US and Israeli governments. They are now in the hands of the Israeli military.
President Joe Biden confirmed the release in a statement on Friday in which he said the US government had been working “around-the-clock” to free American citizens held by Hamas.
“Our fellow citizens have endured a terrible ordeal these past 14 days, and I am overjoyed that they will soon be reunited with their family, who has been wracked with fear,” Mr Biden said, giving thanks to the governments of Qatar and Israel for their help in securing the release.
“As president, I have no higher priority than the safety of Americans held hostage around the world,” he added.
Uri Raanan described the release of his daughter and her mother as the “best day of my life”.