Amazon is once again letting merchants ship packages with FedEx’s ground service after a roughly monthlong ban.

Amazon told third-party sellers Tuesday that they can resume working with the shipper as FedEx is delivering orders on time.

The e-commerce giant had barred outside merchants — who sell more than half of the items on Amazon — from using FedEx’s Ground and Home services for Prime shipments last month because of the carrier’s alleged lackluster performance.

FedEx’s average transit time for ground packages was 2.42 days during the peak holiday season, and 18 percent of packages were delivered early, the company said.

FedEx called Amazon’s decision “good news for our mutual customers.”

With Post wires