SINGAPORE: Citigroup's wealth unit has stopped extending margin loans to its clients against securities of India's embattled Adani group, a source with direct knowledge of the matter said, as the conglomerate reels from a short-seller attack.

The group's flagship firm Adani Enterprises called off its $2.5 billion share sale in a dramatic reversal on Wednesday as a rout sparked by the U.S. short-seller's criticisms wiped billions more off the value of the Indian tycoon's stocks.

Citi's wealth unit decided to cut the loan-to-value ratio for credit against Adani securities to zero on Thursday, said the source, who declined to be named due to the sensitivity of the matter.

Citi declined to comment. (Reporting by Anshuman Daga; Editing by Sumeet Chatterjee and Muralikumar Anantharaman)