(Adds full-year guidance, background and share movement) Feb 5...

(Adds full-year guidance, background and share movement)

Feb 5 (Reuters) - Australia's Downer EDI Ltd (DOW) said on Monday it would book a goodwill impairment charge of A$77 million ($61 million) for its mining business in the half year to Dec. 31 2017.

The mining contractor said the impairment of goodwill was due to non-renewal of two material contracts and delays in securing alternative contracts.

However, Downer said the non-cash charge will not have any impact on existing operations or guidance for fiscal 2018.

The company said it expects 2017/18 underlying net profit after tax and before amortisation of acquired intangible assets of A$295 million before minority interests.

Downer has been diversifying away from mining services to reduce its reliance on the sector, buying companies in parallel industries.

It bid A$1.27 billion for cleaner-caterer Spotless Group Holdings (SPO) last March, eventually winning over 85 percent of Spotless shares.

Downer shares were trading 2.4 percent lower at 2313 GMT, while the benchmark index (xjo) was 1.5 percent lower.

($1 = 1.2647 Australian dollars)