Immigration officials on Tuesday said seven mainland visitors were jailed for up to two months each for working illegally in Hong Kong.

The jail sentences came after officers arrested eight people this month who provided illegal tour guide services and acted as "shopping agents".

Seven earlier appeared at Sha Tin Magistrates’ Courts and at Tuen Mun Magistrates’ Courts, and admitted they had breached their condition of stay.

They were given 54 days to two months in jail.

Officers said one case is still under investigation, and there could be more arrests.

Officers said four women acted as tour guides in Hong Kong. They arranged guided visits for their guests to different tourist attractions in the city, and took photos for them, at an hourly rate of HK$100 to HK$300.

For the other four men, officers said they acted as “shopping agents” by buying food and necessities at supermarkets and restaurants on the mainland, and delivered the goods to customers in Hong Kong. They could earn anywhere between HK$100 and HK$200 for each transaction.

The four men and four women, aged between 19 and 52, were arrested in Hong Kong between January 13 and Monday, after officers posed as customers and reserved services from them through social media.

Immigration Department deputy commander Leung Tsz-chung reminded citizens to be wary of such services.

“When choosing those services, people have to be careful and vigilant, and to make sure the service providers can be employed legally in Hong Kong. Otherwise, people may face criminal liability,” Leung said.