Since Sunday when the visitors peaked, lines of road barriers have been set up outside the centre to form an area where people can queue before being allowed to enter the office.

“The government feared that too many people crowding into the relatively small trading hall will cause accidents, so officers like us who work at other sites were reassigned here these few days,” said an officer who did not want to be named. “Some people arrived as early as 5am.”

Shanghai’s home market has shown signs of “panic buying”, with some new projects selling out in a day, Shanghai media reported last month.

The central government issued several policies in recent months aimed at boosting home sales in smaller cities, including cutting the property transaction tax and lowering down payments.

Most of the easing does not apply to top-tier cities such as Shanghai, which is one of only five mainland cities to still enforce strict home purchase restrictions limiting non-permanent residents to buying just one flat.

Unlike smaller cities that are facing increasing inventory pressure from a glut of supply, home prices have surged in leading cities like Shenzhen and Shanghai due to their robust economies and population inflows.

The centre Baoshan Property Trading Centre was so full of people that staying there for longer than necessary made people feel dizzy, said Yuan Xuejun, who completed the transaction procedures over five hours as a flat seller.

“I came at 8:30am and queued for 90 minutes to get into the centre. My wife and I stood in the wind and cold that dropped below 10 degrees,” he said.

Yuan said he regretted selling his house at the end of January because the price is much higher now. “I think I have lost 300,000 yuan (HK$356,000).”

Home prices in the district have surged more than 35 per cent over the past three weeks and even some small shabby flats at remote locations saw their values double to 50,000 yuan per square metre from the same period of last year, said Zhang Bing, a salesman at the property agency Ai Wu Ji Wu.

“I don’t know why house prices skyrocketed recently and it is not good news for agents, because we don’t have houses to sell,” he said, adding that his agency has 80 per cent fewer apartments for sale than last year.

Zhang, who has sold houses for six years in the city, said he has never saw the home trading centre be so crowded as this time. “The rationale behind the people’s mad buying is that they believe the more expensive a home become, the more urgently they should buy it.”

Lu Dewei, 58, said he felt lucky selling his old house and buying a bigger flat at the beginning of this month.

“We need a bigger home for my son to get ready for marriage. So our demands are rigid,” he said. “I had not expected home prices to jump by such a big extent during such a short time.”

Shanghai saw home prices rise 15 per cent year on year to a record 37,062 yuan per square metre in January, official data shows.

“Panic buying is behind the irrational price surge, as people want to buy before prices rise further,” said Yan Yuejin, Chief Research Officer at E-House R&D Institute in Shanghai.

A new round of property investment and speculation is forming, as the stock market is highly volatile and deposit interest rates are at historic lows, Yan said.

Yi Xianrong, a researcher at the Chinese Academy of Social Sciences (CASS) said the market boom will probably last six months before prices fall from unreasonably high levels.

Not all house trading centres across the city have received a large number of applicants, such as the centres in downtown Jingan District and Putuo District.

“Our business volume is going as usual and we don’t see many more people,” said an official working at Jingan District House Trading Centre, who declined to give her name.

“House prices in our district are already very high and we are a small district with limited home supply, not like in Baoshan.”