Property, plant and equipment, net (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Mar. 31, 2020
Cost	$ 30,613	$ 29,224
Less: accumulated depreciation	(21,113)	(19,785)
Property, plant and equipment, net	9,500	9,439
Building [Member]
Cost	17,278	16,857
Construction-in-progress [Member]
Cost	1,041	604
Plant And Machinery [Member]
Cost	9,829	9,642
Furniture, fixtures and equipment [Member]
Cost	1,879	1,544
Motor vehicles [Member]
Cost	$ 586	$ 577

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