WASHINGTON — Twins Double-A right-hander Alex Meyer missed his last start with soreness in his throwing shoulder, and it has not yet been determined when he will return to the mound.

Meyer, 23, has not pitched for New Britain since June 1, when he struck out 10 while giving up just one run on two hits and two walks in 6 1/3 innings. Meyer, the top-rated pitching prospect in the Twins organization, is 3-3 with a 3.69 ERA in 11 starts this season.

“He had a little shoulder soreness after his last start, so we’re giving him some extra time,” Twins farm director Brad Steil said in a text message.

The news comes as the Twins make an interleague stop to play the Nationals and former Twins center fielder Denard Span. Meyer, a former first-round pick who had never pitched above Class A at the time, was acquired in exchange for Span in a straight-up deal last Nov. 29.

“Obviously I hadn’t heard too much about Alex Meyer,” Span said this weekend of his reaction to the trade. “Pretty sure I’ll be hearing about him soon.”

Meyer went six innings in three straight April starts but has exceeded 5 1/3 innings just twice in his last six outings.

For the season, Meyer has 65 strikeouts in 56 innings. Opponents are batting .221 against him.

Follow Mike Berardino at twitter.com/MikeBerardino.