CHICAGO (Reuters) - All-Star reliever Matt Thornton and the Chicago White Sox have agreed a two-year $12 million contract extension, the Major League Baseball team said on Sunday.

The left-hander posted a record of 5-4 with a 2.67 ERA and a career-high eight saves last season to earn his first All-Star selection.

Thornton's 12.02 strikeouts per nine innings led all American League relievers and he became the franchise's all-time leader with 100 holds.

The 34-year-old is a candidate to assume the closer's role in place of the departed Bobby Jenks.

(Writing by Steve Keating in Toronto, Editing by Ed Osmond)