Mainland couples who give birth to a second child in Hong Kong will be fined for breaching the family planning policy, a senior official has warned.

As more women flock to Hong Kong to give birth to their second child, Zhang Feng, family planning department director of Guangdong province, stressed that this violated China's policies.

"And those who are government employees will even be dismissed from their posts," he said.

"It doesn't matter if they give birth to their second child on the mainland or in other countries and regions, they have violated the country's policies and the province's regulations."

He said that some families had been punished in the past few months after having a second child in Hong Kong, but gave no details.

Zhang made his remarks when a Hong Kong newspaper carried a controversial notice claiming residents' medical services had been affected by the growing number of mainland women who arrive in the city to give birth and gain right of abode there.

According to statistics revealed by Hong Kong Special Administrative Region government, about 88,000 babies were born in Hong Kong in 2010. But more than 41,000, or 47 percent, were to mainland couples, including a large number from Guangdong.

Hong Kong has capped the number of mainland women permitted to give birth in the city at 34,000 this year.

The issue also has prompted calls for an amendment to Hong Kong's Basic Law so that babies born to mainland women are no longer granted permanent right of abode.

"I support Hong Kong government's decision to reduce or limit the quotas for mainland women giving birth in Hong Kong," Zhang said.

China introduced its family planning policy in 1979 to limit births in the world's most populous nation, although the rules have been relaxed in recent years.