Mrs McAreavey, 27, a teacher from Tyrone, was killed on the Indian Ocean island in January 2011.
Two men were cleared of the murder during a seven-week trial almost two years ago but the victim’s relatives claimed the Mauritian authorities had been reluctant to keep them updated since then.
A family statement said: “It was promised by the Mauritian prime minister that justice would be done and would be seen to be done in this case.
“However, as time marches on and the criminal proceedings seem to have ground to a halt, this promise is ringing hollow.”
The statement said the McAreavey and Harte families were more determined than ever that justice be done.
“They are hoping that a settlement can soon be reached with the hotel in respect of the civil proceedings but they are growing increasingly frustrated by the slow progress of the criminal proceedings.”