According to a report by Foxsports.com and confirmed by The Arizona Republic, Arizona Diamondbacks outfielder Justin Upton used the no-trade clause in his contract to nix a proposed trade that would have sent him to the Seattle Mariners. The Mariners were reportedly willing to send a “substantial package” of players to the Diamondbacks in order to acquire Upton, a two-time All-Star.

The 25-year-old Upton finished fourth in National League Most Valuable Players voting in 2011, but tailed off last season when he hit .280 with 17 home runs and 67 RBIs. Arizona GM Kevin Tower has been sifting through offers for Upton throughout the offseason, and the Mariners are in the market to add offense.

They ranked last in virtually every batting category in the American League last season, including runs scored and on-base percentage.

The package reportedly included arguably the two best prospects in the Mariners’ farm system, pitcher Tijuan Walker and shortstop Nick Franklin, along with young relievers Charlie Furbush and Stephen Pryor, both of whom pitched in Seattle last season.

Besides the cost in talent, Upton signed a six-year, $51.25 million contract extension with Arizona in March 2010. It still has three years and $38.5 million remaining. He will be paid $9.75 million in 2013, $14.25 million in 2014 and $14.5 million in 2015.

“We have an interest in improving our club any way we can,” Seattle GM Jack Zduriencik told ESPN in an e-mail this week, while declining to specifically identify his interest in Upton. “We have had a lot of dialogue regarding offense, but we would be open to anything.”

The Texas Rangers, Baltimore Orioles and Atlanta Braves have also been mentioned as potential landing spots for Upton, who became expendable when the Diamondbacks signed free agent Cody Ross recently to a three-year deal worth $26 million.

Upton’s repudiation is another blow to the Mariners, who have yet to make a splashy off-season move. They have attempted to improve their offense with the acquisitions of injury-plagued OF Jason Bay, 40-year-old OF Raul Ibanez, now a three-time Mariner, and Kendrys Morales, obtained in a trade with the Angels for Jason Vargas.

But in the free agent market, they lost out early on Torii Hunter and were outbid for Josh Hamilton by the Angels.