China has fulfilled a promise to curb the number of pregnant mainlanders entering Hong Kong to give birth, the governor of southern Guangdong province said Wednesday.

Thousands of mainland women come to Hong Kong each year to give birth and gain residency rights for their children in the semi-autonomous banking centre, circumventing China's one-child policy.

Hong Kong women have protested that the influx has led to shortages of hospital beds and rising maternity costs, prompting the government to step up enforcement of quotas and entry restrictions.

But Guangdong Governor Zhu Xiaodan said there had been a fall in the number of pregnant women entering Hong Kong as a result of his administration's clamp down on "birth agents".

"You must take the numbers of pregnant mainlanders entering Hong Kong and compare the difference between February and January," he told reporters at a news conference in Beijing, according to Hong Kong's Cable News television.

"There has been a large decrease in numbers," he added, without providing figures.

"Our promise to the Hong Kong Special Administrative Region government has been acted upon, and our actions have been successful."

Zhu was speaking at the annual session of the National People's Congress, China's top legislature.

Birth agents help arrange pre-natal check-ups in Hong Kong, book delivery services and hostels, and arrange care for the women and their babies following the births.

A 29-year-old mainland woman last month became the first birth agent to be charged in Hong Kong under laws forbidding the activity.

Women from mainland China are keen to have babies in Hong Kong -- which has had semi-autonomous status since it ceased to be a British colony in 1997 -- because it entitles their child to rights of abode and education.

Some pregnant mainland women have taken to wearing baggy clothes to hide their bellies as they enter Hong Kong. Others wait until the last minute to give birth in emergency wards rather than reserve maternity beds.

The influx of mainland women has been a major source of recent tensions between Hong Kongers and mainland Chinese.