* Barrick Gold says offer reflects Tanzania risk
* Barrick offer seen as 50% too low
* International arbitration set for July
LONDON, May 31 (Reuters) - Fidelity International, one of the largest shareholders in Acacia Mining, said on Friday Barrick Gold's low bid to buy the Acacia shares it does not already own showed a lack of judgment and it was a "no brainer" to reject it.
The comments in an interview are the first public response from one of Acacia's top shareholders since Barrick's offer earlier this month to buy them out for $787 million.
Barrick Gold spun off Acacia into a separate company in 2010, but owns 63.9% of it. Barrick has said the offer level reflects the risk of operating in Tanzania and it has until June 18 to turn the indicative bid into a firm offer.
Barrick had no further comment on Friday.
Fidelity International said the bid was around 50% too low.
"We are definitely not going to accept the offer," Alexander Wright, portfolio manager at Fidelity International, Acacia's sixth biggest investor according to Refinitiv data, told Reuters. "At this price it's a complete no brainer not to accept it."
Fidelity International, with headquarters in Bermuda and offices in London, owns 3.2 percent of Acacia. It would require 4 percent of Acacia's shareholders to block a compulsory sale and 18 percent to stop a delisting in the case of formal offer, analysts said.
Barrick's Acacia offer follows two years of wrangling over a $190 billion Tanzanian tax bill. A proposed settlement Barrick announced in February included a $300 million payment to resolve the tax claims.
Fidelity International is also a small shareholder in Barrick Gold and Wright said he was also indignant in that capacity.
"I think it reflects extremely badly on Barrick," Wright said of the takeover bid. "The ability to operate fairly and economically in Africa is important for the company. This shows a real lack of judgment."
Wright said his most recent move into Acacia dated from 2017 when he made the assumption an amicable resolution to the company's dispute with the Tanzanian government would be found.
In the absence of a finalised deal with Tanzania, Acacia is expecting to go ahead with an international arbitration hearing in July, with an outcome expected by the end of this year.
Acacia's shares reached a peak above 6 pounds in 2016 and have plunged to less than 2 pounds, although they rallied in February on the announcement of the proposed settlement and better than expected output. (Reporting by Barbara Lewis; additional reporting by Simon Jessop in London and Nichola Saminather in Toronto. Editing by Jane Merriman)