Up to 82 percent of 362 families polled - including spouses and children over eight years old - said their relationships have not been significantly affected by the separation.

Previous surveys always highlighted the negative effects of cross-border work on family life, showing that absentee husbands often have mistresses in the mainland.

But the survey, conducted between October 2005 and March this year by the Chinese University's department of social work, found that relationships can be strengthened.

"Previous research has always chosen interviewees seeking help from government. This survey looked at the subject neutrally instead of digging into the negative side," Professor Lau Yuk- king said.

Half of the respondents said the separations made them value the time they spent together more, while 41 percent of spouses in Hong Kong and 28 percent of spouses in the mainland felt they had more personal autonomy.

One-third of the children said the separations made them independent and did not disrupt their routines. About one-third of spouses said conflicts over parenting had decreased with the one in Hong Kong assuming responsibility. .

Couples said they were able to express their feelings more clearly via e-mails and letters.

"By writing they can express themselves more deeply," Lau said.

Respondents said suspicions over marital fidelity were removed through spouses keeping each other informed about their whereabouts.

Only about 24 percent of spouses in the mainland and Hong Kong said communications had lessened, while 21 percent of spouses in the mainland and 27 percent in Hong Kong felt that sexual activity had diminished.

Most respondents have been working in places nearby, such as Guangdong, for more than 10 years and returned home every week.

Government data shows that, in 2005, some 237,500 workers traveled to the mainland 36 times for an average of three days each time.