Six "ringleaders" of a "Ghana-based criminal enterprise" have been arrested in US over $50m laundering charge, investigators have said.

"The scams we allege in this investigation include romance scams targeting the elderly, business e-mail compromise scams, and even fraudulent Covid-19 relief loans," the FBI's William F. Sweeney said in a statement.

A BBC report said, "Four of the accused had between them controlled more than 45 bank accounts in which more than $50m had been deposited between 2013 and 2020, the statement alleged."

According to the statement, a vast majority of the deposits consisted of large wire transfers and cheque or cash deposits from various US-based individuals and entities.

It added that as part of the investigation, four luxury vehicles suspected to have been purchased with the proceeds of fraud had been seized, the statement said.

The vehicles were two 2019 Rolls Royce Cullinans, a 2020 Bentley Continental GT and a 2020 Mercedes-Benz G63 AMG.