Aug 21 (Reuters) - Fitch on Monday downgraded Hawaiian Electric Industries's credit rating to junk status, becoming the third ratings agency to flag risks associated with the utility's potential exposure to Maui wildfire-related liabilities.

It cut the utility's long-term issuer default rating to "B" from "BBB+" and put the stock on "Rating Watch Negative."

"The rating action reflects potential exposure to large third-party wildfire-related liabilities if utility equipment is determined to have ignited recent wildfires in Maui," Fitch said.

The agency said potential liabilities could be above $3.8 billion, which represents an 'existential threat' to the company. Its shares were down 4.5% in afternoon trading.

Last week, Moody's and S&P Global downgraded the company to junk status. Hawaiian had said it was not looking to restructure but was seeking expert advice amid investor worries over its role in the Maui wildfires that have claimed at least 114 lives.

Shares of Hawaiian have lost nearly 63% of their value since wildfire began on Aug. 8.

(Reporting by Sourasis Bose in Bengaluru; Editing by Arun Koyyur)