Mainland police arrested five more people over the past two days on suspicion of involvement in Hong Kong's biggest kidnapping-for-ransom case in 17 years.

Three men were arrested at locations in Guangdong province, including Dongguan, and two others were found at a Shenzhen guesthouse on Monday as a massive manhunt entered its eighth day following the kidnap and ransom of Bossini apparel heiress Queenie Rosita Law.

A suspect arrested by Hong Kong police will be charged with one count of abduction for financial gain and will appear in Kwun Tong Magistrates' Court on Wednesday.