Ghana has arrested 46 more foreigners suspected of illegal gold mining in the last week, including 43 Chinese, two Indians and an American, an immigration official told AFP Thursday.

The latest raid in the crackdown on illicit gold mining in the central region, which included gunfire but no injuries, raises the number of those arrested to more than 600 since June, mostly people from China.

More than 4,500 Chinese nationals, including those arrested, have left the west African nation since the authorities began enforcing a law that bars foreign nationals from engaging in small-scale mining.

Many left voluntarily after the crackdown was launched.

Regarding the latest arrests, it "seems that all these people were engaged in small scale mining," said Francis Palmdeti, spokesman for the Ghana Immigration Service.

Palmdeti, who provided the citizenship breakdown of those detained in the last seven days, said the American involved was of "Indian origin," and that this was the first US national arrested in the crackdown.

The US embassy in Accra was not immediately available to comment.

Ghana is the continent's second-largest gold producer after South Africa.

Chinese nationals, but also Africans, Russians and others had flocked to the country's central region in search of the precious mineral.

President John Dramani Mahama in June sent a taskforce to the area made up of immigration officials, police and military to clear out the unauthorised foreign miners.

In recent weeks, the foreigners who have stayed have taken to staying in guesthouses or hiding in the countryside, only travelling to their work sites at night, said Palmdeti.

He confirmed that the security forces fired weapons in making the latest arrests, but said no one was hurt.

After an investigation, Ghanaian authorities will decide whether to prosecute or deport those picked up in the sweep.