Investigation continues into June's drilling mud spill off Halifax

Nova Scotia's offshore oil and gas regulator says an investigation is continuing into the cause of a drilling mud spill off the coast of Halifax last month.

The Canada-Nova Scotia Offshore Petroleum Board says the unauthorized discharge of 136-thousand litres of synthetic-based drilling fluid from British Petroleum Canada's West Aquarius Drilling Unit was reported on June 22.

It says a report will be made public after the investigation is complete, but it provided no timeline in a tweet sent Wednesday morning.

The Assembly of Nova Scotia Mi'kmaq Chiefs has called the incident ``extremely concerning'' -- adding that spills and environmental damage have been a constant concern with drilling projects happening off Nova Scotia shores.