Hong Kong and United States authorities may have moved a step closer to reaching a pact on liberalising airspace by agreeing to hold formal talks before the end of April. 'The two sides are discussing dates and are hopeful that they might be able to meet again in a month or two,' said a spokesman for the US consulate in Hong Kong. The breakthrough came just days after Deputy Secretary for the Economic Services Department (ESD) Mary Chow Shuk-ching met for informal discussions on aviation liberalisation with officials from the US Department of Transport. 'After holding talks on February 7 and 8, both parties concluded that there is a basis for moving forward to formal talks,' said the spokesman. A statement from the ESD said both sides had agreed there was enough common ground for a formal round to be held in the near future. An April meeting will come exactly a year after the last round of formal discussions on a bilateral agreement, which ended in a stalemate. The spokesman said Hong Kong had indicated it could not agree to 'open skies' - a total liberalisation of Hong Kong airspace. 'So we'll be discussing a limited deal,' she said. According to the US side, the talks must include a liberalisation of code-sharing, liberalisation of passenger fifth-freedom rights and cargo liberalisation. Fifth-freedom rights enable airlines to drop off then pick up new cargo and fly on to a third destination. Hong Kong has argued any concessions on its part must be met with an opening of the US domestic market. The spokesman was unable to say whether the talks would be held in Hong Kong or the US.