HONG KONG, Oct 20 (Reuters) - China Evergrande Group (3333.HK) said on Wednesday a deal to sell a 50.1% stake in its property services unit has fallen through, delivering a blow to embattled developer"s hopes of avoiding a potentially disruptive default. If it had gone through, the deal with a unit of Hopson Development (0754.HK) to sell half of Evergrande Property Services (6666.HK) would have been worth HK$20.04 billion ($2.58 billion), Evergrande said. The parties said in separate filings to the exchange they were unable to agree on terms of the deal. Evergrande, teetering on the brink of collapse with more than $300 billion in debt, was in talks to sell the stake in Evergrande Property Services (6666.HK) to smaller rival Hopson Development Holdings (0754.HK) for around HK$20 billion ($2.6 billion), sources have previously told Reuters. read more Trading in shares of China Evergrande, Evergrande Property Services Group and Hopson have been halted since Oct. 4, and are expected to resume on Oct. 21. ($1 = 7.7752 Hong Kong dollars)