BOSTON (AP) — State marijuana regulators could approve independent testing laboratories later this month, clearing what's been a key roadblock to opening up the first retail pot shops in Massachusetts.

The executive director of the Cannabis Control Commission, Shawn Collins, told commissioners on Thursday he was "relatively confident" that one or two labs would be ready for a licensing vote at the panel's next meeting Aug. 23.

Massachusetts law requires all cannabis products be independently tested for potency and possible contaminants before they're sold.

The absence of approved labs has further delayed rollout of recreational marijuana sales, which had been targeted to begin July 1.

The commission on Thursday issued provisional licenses to retail stores in Wareham, Plymouth and Easthampton, bringing to six the number of pot shops with preliminary approval to operate.