18.	TRADE AND OTHER RECEIVABLES

	December 31, 2019 US$‘000		December 31, 2018 US$‘000
Trade receivables, net of impairment losses		17,754		21,318
Prepayments		576		807
Contract assets		2,317		1,894
Value added tax		59		63
Finance lease receivables		281		359

		20,987		24,441

Trade receivables are shown net of an impairment losses provision of US$5,443,000 (2018: US$4,202,000) (see Note 29). Prepayments are shown net of impairment of US$1,376,000 (2018: US$1,608,000) (see Note 7).

Contract assets have increased compared to the prior year as the Group shipped more product to customers with cost per test contracts in the last month of the year.

Long-term contract receivable

(i) Finance lease commitments – Group as lessor

The Group leases instruments as part of its business. Future minimum receivables with non-cancellable terms are as follows:

	December 31, 2019 US$‘000
	Gross investment		Unearned income		Minimum payments receivable
Less than one year		523		242		281
Between one and five years (Note 16)		805		402		403

		1,328		644		684

	December 31, 2018 US$‘000
	Gross investment		Unearned income		Minimum payments receivable
Less than one year		617		258		359
Between one and five years (Note 16)		888		412		476

		1,505		670		835

The Group classified future minimum lease receivables between one and five years of US$403,000 (2018: US$476,000) as Other Assets, see Note 16. Under the terms of the lease arrangements, no contingent rents are receivable.

(ii) Operating lease commitments – Group as lessor

The Group leases instruments under operating leases as part of its business.

Future minimum rentals receivable under non-cancellable operating leases are as follows:

	December 31, 2019 US$‘000
	Instruments		Total
Less than one year		3,528		3,528
Between one and five years		27		27

		3,555		3,555

	December 31, 2018 US$‘000
	Instruments		Total
Less than one year		3,498		3,498
Between one and five years		32		32

		3,530		3,530