THE blanket ban on the release of new land for commercial development in Guangzhou announced this week will come as music to the ears of Hong Kong developers. Naturally, the real estate developments proposed in conjunction with the city's new airport have been excluded. Like Hong Kong, the city needs the step to help finance the huge cost of its airport development. But it is exactly the firm-handed approach developers need to quell fears of serious oversupply in the city, and to prop up rentals and prices. Hong Kong-listed companies have a huge amount of money tied up in the Guangzhou office market. New World Development alone has four projects at different stages of completion, including the Yi Hing New World Development Centre and Guangzhou New World Centre. Henderson Land Development has three projects, including block C of River Pearl Plaza. Office rents in Guangzhou may still be quite high, but this could change with China's economic slowdown and a pending flood of new supply. At least 53.8 million square feet of new space was completed in the city in 1994, of which just 20 per cent was for housing. Recently, China conceded it had more than four trillion yuan (about HK$3.67 trillion) worth of unsold property at the end of last year as a result of the nationwide speculative building boom over the past four years. Faced with such a glut, the Ministry of Construction last month declared a ban on approvals for luxury residential building, and ordered city authorities around the country to take emergency action to invigorate demand, though Beijing said nothing about the commercial sector. Even before that, Shenzhen announced its own action package of reforms for both the commercial and residential sectors. Now it is the turn of Guangzhou to show the way. The south led China's open-door call for overseas investment, and now it appears to be taking the lead in applying the brakes. With China now appearing to realise it cannot allow unfettered new development, hopefully it will create for itself a more stable and sober environment in which to invest. Tenants may want to see a crash in Guangzhou rents, but for landlords and developers the city land bureau's actions this week will be seen as a blessing.