The tests that come in addition to customs checks and internal company tests are part of an attempt by President Nana Akufo-Addo's government to tighten control of the sector and tax it appropriately.

Ghana is Africa's second biggest gold producer after South Africa and the metal is the country's top export and its leading earner of foreign exchange.

The government said in February it had begun talks to revive a law mandating the Precious Minerals Marketing Company (PMMC) to certify all exports by mining firms.

Since then the Chamber of Mines has worked with the PMMC to implement the directive, said chamber president Kwame Addo-Kufuor, who is also chief financial officer at Newmont Ghana.

"This is a directive that we welcome ... We believe it will help improve trust amongst stakeholders in the industry," Addo-Kufuor told a meeting of mining and power businesses in the capital.

"PMMC officials now have permanent access to our gold rooms during gold pours for a first-hand view of the processes, and to take assay samples for analysis and comparison and participate in pre-shipment sealing and processes," he said.

Ghana earned $5.78 billion (£4.3 billion) from exports of the metal last year, up 17.6 percent on 2016, central bank data showed.

Akufo-Addo, who took office last year, has said about $5 billion worth of revenues from gold exports to the United Arab Emirates are unaccounted for.

Industry watchers say the unreported shipments represent smuggled gold produced by artisanal miners from Ghana and neighbouring countries.

The government has yet to lift a ban on small-scale mining as part of a general clamp-down on illegal miners last year.

(Editing by Matthew Mpoke Bigg)

By Kwasi Kpodo