CHINA is to press Britain to say exactly how much debt incurred by Hong Kong's new airport will be left after 1997. The demand for clarification of the borrowing of the Mass Transit Railway Corporation (MTRC) and the Provisional Airport Authority (PAA) is likely to be made tomorrow, when experts from the Joint Liaison Group (JLG) Airport Committee meet to discuss the fourth financial package on the airport proposed by the Government last month. The resumption of airport talks - at the expert level - was announced by the two sides yesterday. Mainland organs including the Hong Kong and Macau Affairs Office, the JLG and the Xinhua (the New China News Agency) headquarters in Hong Kong recently completed separate studies on the financing proposals. Under the proposal to break the impasse over the airport plan, the Government has offered to pump more than $60 billion into the PAA and the MTRC. The new funding level would reduce the debts borne by the two corporations to about $20 billion. But a source said it was unlikely the financing issue would be resolved in the near future. The row over publication of the accounts of the failed constitutional talks would also take its toll on the airport negotiations, he said. ''I'm not optimistic that it can be solved within the next few weeks,'' he said. The Chinese side would demand clarification as to whether the borrowing of the MTRC and the PAA would be considered as government debts. ''[We] must know clearly how much we [the Special Administrative Region government] need to undertake for the debts incurred by the two corporations,'' the source said. The 1991 Sino-British agreement on the new airport stated that the Government had to consult China on any debts in excess of $5 billion, he said. Officials have maintained that the $5 billion ceiling is flexible, depending on the actual need in view of the overall financing arrangements. An assistant director to the local Xinhua, Lee Wui-ting, yesterday urged Britain to increase the injection to the project and its associated rail link to cut the financial burden on the future SAR. Although Britain reduced borrowing to $23 billion in the latest financing plan, Mr Lee said this was still equivalent to four times the $5 billion debt ceiling stated in the agreement. Noting that the Hong Kong Government had fiscal reserves in the region of $130 billion to $140 billion, Mr Lee said Hong Kong could afford to increase the injection. ''This can reduce the financial burden on the future SAR,'' he said. Mr Lee declined to give a definite figure for an acceptable level of debt. But he still insisted the 58 hectares of land along the airport railway be included in the annual land disposal programme. Chief Secretary Anson Chan Fang On-sang said she was glad to learn the airport talks were resuming. She hoped China and Britain would have concrete discussions.