Russian gold-developer and explorer Trans-Siberian Gold (LON:TSG) saw its share price sink on Friday, after warning that profits were likely to fall going forward.

The group’s total gold production for the financial year 2017 of 36,714 ounces exceeded previous guidance, but it warned that profits were likely to fall heading in 2018.

The miner, who is focused on low cost, high grade mining operations and stable gold production in Russia, forecast production in 2018 of of 36,000oz-to-40,000oz.

Revenue remained strong in 2017, up slightly to $43.5 million from $42.2 million the year before. However, “operational challenges” had cut first-half profit to $0.5 million, down from $5.4 million in 2016.

“Whilst operations improved significantly in the second half, it is expected that pre-tax profits for FY2017 will be lower than FY 2016,” the company said.

Shares in Trans-Siberian Gold are currently down 2.44 percent at 40.00 (0849GMT).