* Share price falls 4 percent

* International arbitration hearing set for Q3 (Adds comment from Acacia, detail, share price movement)

April 25 (Reuters) – Acacia Mining Plc reported a slump in underlying core earnings on Thursday as it struggled with production issues at its North Mara gold mine in Tanzania, where it said pressure was building for a settlement of its row with the government.

Acacia, majority-owned by Barrick Gold, is embroiled in a long-running tax dispute with Tanzania. It has cut output by a third since the government banned the export of mineral concentrates in 2017.

London-listed shares of the mid-cap company were down 4 percent by 1020 GMT, deepening a 12 percent drop year to date.

Underlying earnings before interest, tax, depreciation