17.	TRADE AND OTHER RECEIVABLES

	December 31, 2018 US$‘000		December 31, 2017 US$‘000
Trade receivables, net of impairment losses		21,318		17,242
Prepayments		807		891
Contract assets		1,894		2,107
Value added tax		63		-
Finance lease receivables		359		500

		24,441		20,740

Trade receivables are shown net of an impairment losses provision of US$4,202,000 (2017: US$3,590,000) (see Note 28). Prepayments are shown net of impairment of US$1,608,000 (2017: US$1,651,000) (see Note 6).

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

Leases as lessor

(i) Finance lease commitments – Group as lessor

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

	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 15)		888		412		476

		1,505		670		835

	December 31, 2017 US$‘000
	Gross investment		Unearned income		Minimum payments receivable
Less than one year		860		360		500
Between one and five years (Note 15)		1,204		519		685

		2,064		879		1,185

The Group classified future minimum lease receivables between one and five years of US$476,000 (2017: US$685,000) as Other Assets, see Note 15. 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, 2018 US$‘000
	Instruments		Total
Less than one year		3,498		3,498
Between one and five years		32		32

		3,530		3,530

	December 31, 2017 US$‘000
	Instruments		Total
Less than one year		3,959		3,959
Between one and five years		90		90

		4,049		4,049