The bidding war for free agent outfielder Carlos Beltran is heating up as the veteran reportedly received a three-year offer worth $48 million.

ESPN's Buster Olney posted the development on his Twitter account, but he is unsure what team offered the contract although he quickly added that it could be the Seattle Mariners, who are getting aggressive on the free agency market.

"Carlos Beltran is said to have a three-year offer for $48 million in hand. Not sure if it's the Mariners, but Seattle is being aggressive," Olney said.

If the speculations are accurate, the Mariners will be an additional threat to the New York Yankees, which is perceived as the most likely destination of the 36-year-old veteran.

Aside from the Yankees and the Mariners, the Kansas City Royals are also in play for Beltran, who started his celebrated 16-year-career in Kansas City.

Beltran began his professional career in 1998 and spent five seasons with the Royals, recording four 100-run and 100-RBI season during that span, before he was traded to the Houston Astros in 2004.

The New York Post confirmed that Beltran arrived in Kansas City on Monday and was scheduled to meet with Royals officials on Tuesday to talk about their possible reunion.

"Beltran arrived in Kansas City on Monday and is there Tuesday as well to meet with club officials and listen to the Royals' small-market, big-money pitch. The Royals may be willing to go to three years to sign Beltran," the NY Post reported.

Beltran is one of the top players on the Yankees' wishlist, but they might be forced to give into the demands of Beltran for a three-year deal instead of the reported two-year deal offered by the Yankees.

"The Yankees would love to ink Beltran to a two-year deal, but Beltran is hopeful of securing a coveted three-year deal, which may be the final contract of his career," the NY Post noted. "The Yankees could win this money battle if they go to three years with Beltran, but it remains to be seen if they are willing."