Beijing's migrant population will be better managed and provided with more services as part of efforts to ensure a safe Olympic Games, Wang Anshun, the city's deputy Party chief, said yesterday.

"With the rapid increase in the number of migrants, how to manage and serve them has become a key issue in the city's development and in the provision of a safe Games," Wang said at a national security working conference in Guangzhou.

To achieve its goal, the government must have a full picture of the situation, he said.

"We are conducting a comprehensive survey to find out how many migrants there are, what their backgrounds are and where they are living. More than 50,000 people are involved in it," Wang said.

Last year, the municipal government estimated there were about 5.3 million migrants in Beijing - about 30 percent of the population. Others, however, have said the number is much larger, as not all migrants register at police bureaus.

Migrants can pose security difficulties, an official said recently.

Miao Lin, director of the population management division of the city's police bureau, said migrants were responsible for more than 70 percent of all crime in Beijing.

On the approach to the Olympics, experts have warned of terrorist attacks by people from outside the city or country.

Having a clear picture of the migrant population and information about the properties leased to them is very important to prevent attacks, as terrorists are usually not natives, Boaz Ganor, founder of the Israel-based International Institute for Counter-Terrorism, said last month.