The United Nations agency that coordinates international mail deliveries says it is working to get small parcels dispatched to the United States again by resolving confusion over the pending elimination of a US tariff exemption for low-cost imports.

The Universal Postal Union said it sent a letter to US Secretary of State Marco Rubio on Tuesday to express concerns the agency's member countries have about the end of the 'de minimis exemption,' including requirements for collecting and transmitting new customs duties.

The postal service operators of more than 30 countries, including almost all of the ones in Europe, have limited or stopped shipping all or most US-bound parcels valued at USD 800 or less, which has been the cutoff for imported goods to escape customs charges.