Ryan Dempster has posted 16 saves in 18 opportunities this season. ((Jonathan Daniel/Getty Images))

The Chicago Cubs put closer Ryan Dempster on the 15-day disabled list Tuesday because of a strained left oblique muscle.

The move is retroactive to June 23.

Dempster, from Sechelt, B.C., suffered the injury in the ninth inning of last Friday's 5-1 victory over the Chicago White Sox at U.S. Cellular Field.

Dempster is having a banner season for the Cubs, posting a 1-3 record in 33 relief appearances with a 3.38 earned-run average and 16 saves in 18 opportunities.

The 30-year-old right-hander has yielded just 21 hits in 34 2/3 innings pitched, striking out 33 batters and walking 14.

Dempster is 58-71 lifetime with a 4.79 ERA, 75 saves, eight complete games and two shutouts in 354 appearances, including 162 starts, since making his major-league debut with the White Sox on May 23, 1998.

He also has pitched for the Florida Marlins, Boston Red Sox, Cincinnati Reds and Cleveland Indians.

Dempster signed a three-year, $15.5-million US contract with the Cubs on Nov. 29, 2005.

With files from the Associated Press