Mascherano has been closely linked with a move to Spanish giants Barcelona, while Reina has been linked with a move to Chelsea.
Benitez said of Mascherano: “I was talking with him and his agent the other day and it is true Javier is happier.
“The conversations were very positive. When you talk with Javier he is very settled and happy.
“Everyone knew about some clubs (being interested in him) but talking with us he was fine.”
Benitez added, when asked if a deal could be signed before the end of the season: “I think so.”
“Pepe (Reina) is another key player and it is 100% he will continue with us,” Benitez said of Reina.
“Everything is very close. I think we will have news about Reina and Mascherano very soon.”