China tightened restrictions on exports of masks and other personal protective equipment (PPE) on Friday, calling for shipments of the items to be subjected to a mandatory customs inspection, with immediate effect.

The new rules mark the latest bid by China to balance the global demand for PPE to help treat the rising number of cases of the new coronavirus, while ensuring that manufacturers and sellers do not flood the market with uncertified or shoddy products.

The regulations follow highly publicized complaints from some governments and hospitals that they received PPE from China that they considered faulty.

In late March, Dutch officials recalled tens of thousands of masks delivered to the Netherlands from China, stating they did not meet quality standards.

The regulations published on Friday, from China's customs agency, require companies manufacturing PPE for export to submit extra documentation and go through a government-led inspection process.

This month, authorities established rules requiring mask exporters to provide documentation ensuring their products are registered to be sold in China, and also meet the relevant regulatory standards in the destination country.

Industry experts say the new inspections could lengthen the approval process for shipments of the equipment by days or weeks.

As the coronavirus has subsided in China and spread around the world, a global shortage of masks and other PPE has emerged.

Companies such as LVMH and IKEA launched production lines to help meet the demand, along with scores of large and small manufacturers across China. Many of the new manufacturers have little experience producing medical-grade products and come from sectors unrelated to health.

Maggie Chen, who runs a Shenzhen-based consultancy that helps companies comply with import and export regulations, says that in the short term, the new regulations will further shrink the number of masks on the market and cause prices to increase.

But she said they mark a necessary step in ensuring that the PPE made in China meets international standards.

"It's good for the market that there are new manufacturers who are emerging to relieve the shortage of masks," she said.

"But masks are medical products, and it's also good for the market to regulate them."