OAKLAND -- A Major League source confirmed Friday that the A's and right-handed reliever Grant Balfour have agreed on a two-year deal with a club option for 2013, pending a physical.

The A's have not announced the deal and won't do so until the physical is complete, though the Associated Press reported that Balfour is set to earn $3.75 million in 2011 and $4 million in 2012. His club option for 2013 is worth $4.5 million and includes a $350,000 buyout.

Balfour, 33, is a seven-year veteran who most recently posted a 2.28 ERA and 1.08 WHIP while averaging 9.1 strikeouts and 2.8 walks per nine innings spanning 55 1/3 frames for the Rays last year. He has tallied 207 strikeouts in 181 innings over the past three seasons, numbers that represent the third-best strikeout ratio of any American League reliever over that time period.

The Australian native is classified as a Type A free agent, so Oakland -- whose first-round pick is protected -- will have to hand over a second-round choice to Tampa Bay once the deal is finalized. The club will also have to trim its 40-man roster by one to make room for Balfour.

The righty's presence bolsters an already formidable A's bullpen, which includes the likes of two-time All-Star Andrew Bailey, Michael Wuertz, Craig Breslow, Brad Ziegler and Jerry Blevins. Healthy versions of Joey Devine, Rich Harden and Brandon McCarthy also figure to be possible additions.

The A's, looking to build on a 2010 campaign that resulted in a 81-81 record and second-place AL West standing, have proved to be the busiest club in their division this offseason. That much is evident not only by the signings of hurlers Balfour, Harden and McCarthy, but in the offensive additions of Hideki Matsui, Josh Willingham and David DeJesus.