HONG Kong and China are set to become the cornerstone of expansion in Southeast Asia by Tarmac, one of Britain's top 10 building contractors. This follows an unprecedented asset swap agreement with rival firm Wimpey last week that will transform Tarmac into one of the world's largest construction and minerals groups early next year. Tarmac group chairman Neville Simms said Hong Kong and China would be key areas for growth, especially in aggregates - stone, concrete, road surfacing and building materials - if the deal received the green light. 'We would certainly hope to build on Wimpey Asphalt's position to make further inroads into mainland China if possible,' he said. The firm also was keen to develop opportunities in Indonesia, Taiwan, Malaysia and Singapore where it already had offices. Other important markets identified by Tarmac before the deal was announced were Thailand, where it planned to open an office, and possibly the Philippines and Vietnam. Expansion in Southeast Asia, where it had established contracting and professional services businesses, was a significant part of Tarmac's strategy, according to Mr Simms. That reflected the region's booming need for infrastructure. The firm was targeting turn-key power, tunnelling, railways, ports, airports and water supply and treatment projects. The company also was anxious to develop its overseas business to offset the collapse in the British construction market caused by the British Government's preoccupation with privately financed public works projects. Road building in Britain, one of Tarmac's main markets, had virtually come to a standstill, because the government wanted private finance for all but the smallest projects. This helped persuade Wimpey chief executive Joe Dwyer to pull out of contracting completely. Mr Simms and Tarmac Construction chief executive Brian Pellard are due to make a fact-finding tour of the Pacific Rim operations by the end of this month. That was partly to assess future growth markets, but it also would consider how much duplication there was between existing Tarmac-Wimpey operations. Both had offices in Singapore. In Hong Kong, Tarmac operates as Tarmac Construction International and through its worldwide joint venture, TBV, with US engineer Black & Veatch. On the contracting side, Tarmac Construction Far East has a US$72 million order on the Chek Lap Kok airport railway project, but it does not have a formal office established.