(Reuters) - Citigroup Inc <C.N> said on Monday it did not experience any "significant negative impact" on its results or client activity as a result of Britain's vote to exit the European Union.

Citi said in a regulatory filing that while market activity increased following the referendum in the UK, the bank expects the operating environment to continue to be challenging. (http://bit.ly/2aFQlwd)

The bank's UK asset exposure was $108.4 billion as of June 30, according to the filing.

Citi said only 30 percent of its corporate loans booked in the UK were to UK-domiciled entities, while the rest were mostly to European counterparties.

The bank left its estimate for possible unreserved legal costs, as of June, unchanged at $3 billion.

(Reporting by Sruthi Shankar in Bengaluru; Editing by Maju Samuel)