The Vietnamese government has awarded medals of honour to four Swiss experts for their contribution to improving Vietnam's water and sanitation.
The medals were presented by the Vietnamese ambassador to Switzerland on Tuesday.
The specialists all belong to the Swiss Federal Institute of Aquatic Science and Technology (Eawag), and have worked in Vietnam since 1998.
They have been honoured for the applied research they have carried out with Vietnamese colleagues to whom they have passed on a wealth of practical know-how.
As a result of the partnership, the quality of the drinking water supplied to two million people in Hanoi has been greatly improved.
They also developed ways to trace and remove arsenic from the drinking water of several million people in the densely inhabited river deltas.
In other research they worked out the best way to deal with the sewage and wastewater problem from the fast-growing cities and industries. After the success of pilot projects, their solution is now being applied generally.
The medal of honour is rarely given to foreigners.