The government has no intention of changing the one-way permit system, as a third of local marriages are cross-border ones and there is a need for family reunion, Secretary for Security John Lee Ka-chiu said.
Lee made the comments in a Legislative Council meeting to discuss a non-binding motion by lawmaker Gary Fan Kwok-wai to halve permit quotas due to the increasing strain on the SAR's public resources.
Under the current system, Hong Kong receives at most 150 immigrants from the mainland a day, but the SAR does not have the right to vet applicants.
Speaking for his motion, Fan said medical resources are being drained by the growing population, mainly due to increasing numbers of new immigrants from the mainland.
"Hong Kong is now like a severely overloaded ship. With too many people, it will sink," he said.
Fan also suggested in the motion establishing a return mechanism so that new immigrants who cannot adapt to life in Hong Kong can retain their mainland household registration and go back for resettlement.
The security chief, however, said the single-way permit system aims at allowing mainland residents to come to Hong Kong for family union in an orderly manner.
Lee said one third of the total registered marriages in Hong Kong are cross-border ones and no declining trend in the long term is foreseen.
So it is necessary to let Hong Kongers' mainland spouses and children to reunite in Hong Kong, he said.
As for the suggested establishment if "a return mechanism", Under Secretary for Security Sonny Au Chi-kwong said the government has been in discussions with the mainland over this, adding that Hong Kong will make an announcement if there is any new arrangement.
Lawmaker Steven Ho Chun-yin objected to the motion, saying mainland new immigrants add to the city's labor force.
Even Li Ka-shing, Hong Kong's richest man, came from the mainland too, he said.
Lawmakers should not incite hatred against new immigrants, attributing all problems to a particular group, he said.
The motion was defeated in the council, with 13 votes in support versus 38 against. Three abstained.
Dating company HK Romance Dating conducted a survey by interviewing 372 single men and 270 women in February and March.
It found that 48 percent of the men find marriage with mainlanders acceptable, with women from Guangdong being their choice.
Some 61 percent also think mainland women are more caring.
Only 44 percent of women would like to marry a man from the mainland, Shanghai in particular, but more than half said there is no particular reason.