About 20 freelance Amazon Japan delivery workers staged a single-day strike on Friday in the western prefecture of Nagasaki.

A union in Tokyo says it is the first time freelance delivery staff for Amazon have gone on strike in Japan.

The workers say a subcontractor for the e-commerce giant has announced it will terminate a contract linked to them, without adequate explanation.

Their union says in December a primary subcontractor for Amazon Japan informed a second-level subcontractor that it will terminate their outsourcing contract on April 8.

The workers have contracts with the secondary contractor.

The workers requested collective bargaining so they could continue delivering products. But they said the primary subcontractor told them on Thursday that it would not agree to collective bargaining. They also said the firm told them it is not in the position to handle the transfer of contract after the current contract ends.

One delivery worker said they could not understand why no explanation was given over terminating the contract.

The primary subcontractor said it would not comment on details of the matter. The firm said it expects the strike will have no impact on deliveries to customers on Friday.

Amazon Japan said no delays in deliveries have been reported.