Potential customers look at a model of a real estate development in Yichang, Hubei province.[ZHOU JIANPING / FOR CHINA DAILY]

SHANGHAI/SHENZHEN - Two major Chinese cities of Shanghai and Shenzhen on Friday issued a slew of policies to tame their property markets, including raising down payment requirements for second home buyers.

Under the new rules in Shanghai, which came into effect on Friday, those who already own a house must make at least a 50-percent down payment, instead of the previously required 40 percent, when applying for home loans. The minimum down payment rises to 70 percent if the home's size and price surpass the criteria for an ordinary house.

Non-local buyers must also prove they have paid income tax and social security premiums in the city for five consecutive years, up from two years under the previous requirement.

The city will ban developers and housing agencies from offering certain loan services to buyers. It also vowed a tougher clamp-down on house speculation and price-gouging.

The regulations are meant to curb surging prices in the city's property market resulting from "irrational emotions," speculation and illegal practices by some companies and agencies, said Gu Jinshan, a director with the city's housing and urban-rural development commission.

In Shenzhen, the municipal government issued similar policies late Friday night.

In a statement, it said those who buy the first home but have borrowed home mortgages over the past two years or already owns one home but have paid off mortgages must make at least a 40-percent down payment, instead of the previously required 30 percent, when applying for home loans.

Non-local buyers must have paid income tax and social security premiums for three consecutive years, up from one year under the previous requirement, if they wish to buy a house.

Shenzhen authorities also ordered to beef up measures to guard against financial risks in the property sector.

The government said it banned financial institutions including Internet finance companies and small-sum lending firms from offering margin lending to home buyers.

It also called to strengthen supervision and crack down on various violations.

Meanwhile, the Shenzhen government said it will increase land supply and build more government-funded houses to balance the market demand and supply.

It added that in the five years to 2020, it planned to build 400,000 government-funded houses.

In February, new home prices in Shanghai jumped about 20 percent year-on-year, while in Shenzhen, prices soared 72 percent, showing signs of overheating in the top-tier cities.