CHINA and Britain expressed optimism yesterday about finally reaching an agreement on the financing of the Chek Lap Kok airport. The Chinese team leader of the Joint Liaison Group, Guo Fengmin, said he believed an agreement would be forthcoming in the ''very near future''. He said experts from the two sides would meet soon to iron out differences over the Airport Corporation Bill. Meanwhile, the Secretary for Works, James Blake, told Legislative Councillors he expected an agreement soon. Tabling a $820 million funding request, Mr Blake said it was necessary for the works to continue pending an airport agreement. The money was needed for the construction of the airport railway's immersed tube between West Kowloon and Central. Mr Blake said it was essential the work be done at the same time as the West Harbour Crossing in order to minimise disruption to water traffic. Because of delay with the Central reclamation project, this part of the tunnel will come into service in April 1998 - nine months after the scheduled opening of the airport. Mr Blake said most of the airport core projects could be completed by July 1997, provided an agreement on the financing arrangements was reached soon. Currently, 21 contracts - representing 70 per cent of the airport railway work - are under tender arrangements by the Mass Transport Railway Corporation (MTRC). Twelve will be ready for tender in the next six weeks. For these contracts, worth $10.5 billion, the contractors involved have agreed to hold their prices for up to a year. Describing this as a prudent arrangement, Mr Blake said it would enable works to be started as soon as an airport deal was struck. ''We have confidence that we can see the excellent progress on the ground be translated into both the airport and airport railway as soon as the present funding negotiation are complete,'' he said. Responding to the comment by the director of Hong Kong and Macau Affairs Office, Lu Ping, that the airport would be completed by the changeover, Mr Blake said he believed Mr Lu was expressing confidence. Mr Lu knew that as soon as the negotiations were settled, Hong Kong had the ability and track record to complete the works speedily and efficiently. The Government's funding request again came under fire from legislators. The Liberal Party's Steven Poon Kwok-lim said the Government should release details of the fourth financing package before asking for money for the MTR. He questioned whether the funding request was within the amount of equity injection proposed by Britain in its fourth financing proposal submitted in February. Mr Poon also asked for greater accountability on the part of the MTRC, which is wholly owned by the Government. The funding proposals will be passed to the Finance Committee for endorsement.