More public and subsidised housing will be built in addition to the 75,000 flats announced in his policy address, Chief Executive Leung Chun-ying said on radio yesterday. He also claimed that neither of his two predecessors were as determined as he is to tackle the city's housing woes. Later, on a television programme, Leung dismissed criticism that he had not been doing enough to curb property prices. He stressed that he would not allow "developer hegemony" and would increase the supply of homes when necessary. Speaking on RTHK Radio 3's Letter to Hong Kong programme, Leung pledged to increase the short, medium and long-term supply of public and private housing and maintain a stable property market. "Since [the policy address] we have successfully increased the plot ratio of four residential sites. One of these sites will provide Home Ownership Scheme units. "In March, another site will be presented to the Town Planning Board for rezoning to public rental housing. If approved by the board, this will add to the present target of 75,000 units in the next five years," he said. Meanwhile, three think tanks - The Professional Commons, Local Research Community and Harmonic Hong Kong - announced yesterday a plan which they say can raise the number of units at the Kai Tak redevelopment site from 32,540 to 42,349. The plan called for the relocation of the three proposed sports stadiums within the site so that more land is released for housing. The think tanks are seeking a meeting with the Home Affairs Bureau to discuss their proposal. During the radio show yesterday, Leung also spoke on his other initiatives. He said he had set aside HK$10 billion as subsidies to phase out heavily polluting commercial diesel vehicles. The government is expecting more than 80,000 vehicles to be phased out under this programme. He also said the government was stepping up efforts to cut emissions from the big ships. "Further, we shall work with the Guangdong Provincial Government to explore the feasibility of requiring ocean-going vessels to switch to low-sulphur diesel while berthing in Pearl River Delta ports," Leung said. On trade, he announced that a high-level joint working group in the Ministry of Commerce would be set up to improve the free trade agreement with the mainland. An Economic and Trade Office would also be set up in Wuhan to better serve Hongkongers and businesses.