An elementary school in Shenzhen, a city in south China's Guangdong Province apologized on Thursday for its announcement two days ago saying it would consider a family's property size and length of ownership in the admissions process.

The announcement said that students had to prove that their families had owned the apartments for a certain period of time. The smaller the apartments, the longer the required ownership time. 

Families whose apartments are 30 square meters or less were asked to demonstrate at least six years of ownership and residency, while those with homes larger than 50 square meters would just need to prove one year's ownership. 

The decision was criticized for discriminating against children from lower-income families, who cannot afford larger homes. 

The school said the move was put forward because education resources were extremely limited. It aimed to ensure kids from families who have registered permanent residence, or Hukou in Chinese, and originally live near the school get access to education near their homes. And it is designed to prevent a shortage of positions caused by families who buy properties near schools just to qualify for enrollment. 

According to a document released by the city's Education Bureau in April 2018, each public school covers its own district of neighborhoods and is not allowed to take in students from other districts. Documents proving ownership of property within the district have to be provided to prove their kids' eligibility for education in these areas.

Similar policies are also being adopted by other major cities in China including Beijing, Shanghai, Hangzhou, Xi'an, and Tianjin. It has prompted some families to purchase properties of relatively small size near certain public schools for better education for their kids, leading to rising real estate prices.