By Monica Whitlock
BBC Central Asia corespondent
Turkmenistan has closed down all its international courier companies, the main postal link between the country and the outside world.
The Ministry of Communications said couriers' licences would not be extended, without explaining why.
Turkmenistan is already an extremely isolated country and the move will hit hard, especially businesses and the foreign community.
Big couriers like Federal Express and DHL are lifelines to the outside world.
Many embassies and most businesses send all their documents and other post through them.
The DHL office in the capital, Ashgabat, confirmed that it was no longer operating and was unable to deliver a mounting backlog of post.
An employee said the company was in talks with the government and she hoped the service would resume.
No reason has been given for the abrupt move, but it is in keeping with Turkmen government policy, which controls all communications tightly.
Telephones are monitored, internet use is controlled and TV and radio stations broadcast almost no news.
Ordinary Turkmens, for example, know almost nothing about the fall of the Kyrgyz government last month, even though both countries are in Central Asia.
Businesspeople also point to another possible motive.
Without the international couriers, diplomats and companies may have to use a Turkmen service which the government wants to promote.
The service is slow, unreliable and clearly open to official scrutiny.
Working in Turkmenistan is already extremely difficult. The end of the couriers will make it even more so.