Beijing is facing a crisis of fast population expansion as the city's residents hit nearly 20 million by the end of last year, far more huge than the city government had anticipated.

The rapid growth of population has become an urgent problem, Beijing News quoted an unnamed expert today.

The massive amount of residents and ever increasing inflow of migrant workers into the city are straining the city's resources, the expert warned.

According to a city development plan issued in 2004 by the State Council, the Chinese Cabinet, Beijing's population is expected to reach 18 million by 2020. The number hit 19.71 million by the end of 2009.

The city needs to ship in 98 percent of the energy it consumes. The city also faces a water shortage crisis as it was hit by draught in 11 consecutive years.

The soaring population has left a great pressure on the city's schools, public transport system and other facilities, the expert said.