MEXICO CITY—Mexico's oil regulator announced on June 13 the cancellation of auctions set for October to pick joint-venture partners for national oil company Pemex in seven onshore areas.

The cancellation was requested by Pemex, and marks a fresh blow to an energy reform enacted by Mexico's previous government that allowed the firm to partner with private oil companies for the first time in a bid to reverse declining crude output.

The regulator's announcement to cancel the tenders confirmed a Reuters report from earlier in the day.