Property, plant and equipment, net (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Mar. 31, 2019
Cost	$ 29,224	$ 29,436
Less: accumulated depreciation	(19,785)	(19,845)
Property, plant and equipment, net	9,439	9,591
Building [Member]
Cost	16,857	16,890
Construction-in-progress [Member]
Cost	604	597
Plant And Machinery [Member]
Cost	9,642	9,838
Furniture, fixtures and equipment [Member]
Cost	1,544	1,475
Motor vehicles [Member]
Cost	$ 577	$ 636

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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