CHINA yesterday offered a double-barrelled boost to Hongkong's confidence by suggesting that it was willing for talks on the airport to get under way again and predicting that success in talks on political matters would send the Hang Seng index soaring. A delegation of 14 Hongkong district board chairmen yesterday revealed that a top Chinese official in charge of Hongkong affairs, Mr Lu Ping, had told them that Beijing was willing to reopen the airport talks. But for this to happen, Britain must be able to reduce the total amount of borrowings for the infrastructure projects to less than $5 billion. Yesterday, Mr Lu told a business delegation headed by Mr Hu Fa-kuang that ''it would not be impossible'' for the Heng Seng Index to reach the 8,000-mark if tomorrow's talks over the 1994/95 electoral arrangements succeeded. The protracted Sino-British dispute over the constitutional reform plan was seen as a major factor barring any meeting of the Sino-British Airport Committee, which has been suspended for almost six months. The lack of meetings has already stalled some of the airport projects, including the construction of the rail link. But Mr Lu, the director of the State Council's Hongkong and Macau Affairs Office, offered fresh hope for resolving the impasse when meeting the district board chairmen on Monday. According to Central and Western District Board chairman Mr Ambrose Lau Hon-chuen, Mr Lu said Beijing was willing to resume the airport talks if the level of debt could be substantially reduced. The Deputy Secretary for the Treasury, Mr Stephen Selby, had earlier urged China to give a direction in formulating a new financial package for the Chek Lap Kok facility and its associated rail link. Under the Memorandum of Understanding of the new airport projects, borrowings should be below $5 billion. Mr Lu told the chairmen that the borrowings under the existing financial package had far exceeded the $5 billion mark, Mr Lau quoted the director as saying. Although there had been suggestions to replace the Chek Lap Kok airport with Shenzhen airport, a Chinese source yesterday said the proposal was an opinion raised by Hongkong people only. Meanwhile, according to the China News Service, Mr Lu, while noting the possibility of the Hang Seng index hitting a new record, said: ''On the contrary, the stock market will certainly slump if there is no agreement [on the talks on political reform].'' Mr Lu drew the rosy picture as the two sides apparently tried to lower the temperature while negotiators finalised preparations for the talks. Although Mr Lu rejected discussions on the political blueprint of the Governor, Mr Chris Patten, at the talks on Monday, he refrained from making further comment yesterday. Arriving in Hongkong to prepare for the talks, Britain's Ambassador to China, Sir Robin McLaren, declined to be drawn on Mr Lu's remarks, saying: ''We shall have to talk about all these matters.'' In Beijing, Mr Lu told the Hongkong delegation that the local stock market would already have collapsed because of the political row if not for the booming mainland economy. Mr Lu insisted that it was the economy, rather than politics, which most worried Hongkong people, adding that the territory should under no circumstances become a ''political centre''. On the upcoming talks, Mr Lu emphasised that China ''has no bottom-line'' but the Joint Declaration, the Basic Law and the diplomatic exchanges between the two sides. British and Hongkong officials, including Mr Patten and Sir Robin, yesterday held a series of internal meetings, including a special Executive Council meeting last night to finalise the British side's negotiating strategy. Sir Robin and his aides will fly to Beijing today. Commenting on the talks, Mr Zhang Junsheng, a vice-director of the local branch of the New China News Agency, ruled out the possibility of discussing the criteria for vetting legislators who could straddle 1997. Senior Executive Councillor Lady Dunn agreed that tomorrow's talks should be based on the Basic Law, the Joint Declaration and the previous understandings between the two countries.