According to Nitsana Darshan-Leitner, director of Shurat HaDin, an Israeli legal group representing the families, the justice ministry was asked by a New York court to supply certain documentation, but ignored the request.
"The federal court in New York made the request for the documents half a year ago. The request went unanswered... So we sent a letter weeks ago asking what's going on, which also went unanswered," Darshan-Leitner told AFP.
The ministry was not immediately available for comment.
This is the latest twist in a complex billion-dollar civil lawsuit launched in a New York court in October 2012 by the Israeli families of eight teenagers shot dead by a Hamas gunman at a Jerusalem seminary in 2008.