In response to netizens' doubts on why a pregnant woman from the mainland was refused to enter Hong Kong, the Hong Kong Immigration Department said Tuesday that women who are more than 28 weeks pregnant can be denied entry, unless a maternity booking issued by a Hong Kong hospital is presented.

On Sept 20, the woman and her husband were detained at Hong Kong airport, questioned by customs for half an hour and told to go back as "the woman was in late pregnancy," according to customs staff.

She was denied entry into Hong Kong by customs for fear that she might give birth in the city, stirring fierce debate online.

However, the woman and many netizens said the Hong Kong government didn't have the right to refuse entry to the woman after she had provided enough proof, including a maternity booking with a Beijing hospital that said she had no plan of giving birth in Hong Kong.

"I'm here to shop and relax, not to have babies," the woman wrote on her blog, which has become widely circulated. "Who would come to Hong Kong to give birth with only one backpack?"

In the past couple of years, tensions have mounted as mainland mothers have flocked to give birth in Hong Kong to acquire permanent residency for their babies. Local women, however, have seen a strain on hospital wards and resources such as baby formula.

In 2013, Hong Kong chief executive Leung Chun-ying banned mainland mothers from giving birth in public hospitals and ordered intensified border checks of pregnant women.

From January to August 2014, Hong Kong shut its door to about 3,500 pregnant women from the mainland.