CHEUNG Kong Holdings and Pacific Concord Holding have paid a land premium of about $450 million for the long-awaited swap with the Government of the Ma On Shan residential site for the Tsing Yi oil depot site. Government land agent Nigel Burley confirmed yesterday's deal but declined to disclose the land premium, which sources said was about $450 million. He said the developers would be given six months to demolish the oil depot while the Ma On Shan site was already available for development. Cheung Kong, as a veteran land negotiator with a 50 per cent stake in the project, has been talking with Buildings and Lands Department officials on the deal for more than a year. The premium issue had taken much longer than expected to settle because the two parcels of land - for industrial and residential use, respectively - could not be directly compared. Its ultimate settlement is believed to have been well received by the stock market as the Sha Tin site will mean another contribution to the land bank of the developers. Located near Henderson Land's Sunshine City project in Sha Tin, the site covers an area of 300,000 square feet. Property analysts noted that a premium of $450 million would be an insignificant sum because of the site's potential for a huge residential project. With plot ratios of six times and 9.5 times, respectively, for the residential and retail developments, the project's total buildable area is estimated to be about two million square feet. Assuming construction and interest costs of $600 a square foot, the project's total investment would be about $1.7 billion. ''The land swap should be viewed as in favour of the developers, given the low land price of $225 per square foot for the Sha Tin site,'' a property valuer said. However, Mr Burley insisted the swap was based on market values without any concession to the developers. ''With an area of about 6.5 hectares, the Tsing Yi depot was a really large site. Taking the swap into account, the developers are actually surrendering a valuable property,'' he said. Cheung Kong bought a 50 per cent interest in Concord Oil, the crown leaseholder of the Tsing Yi depot, for $690 million in November 1990. The site was independently valued at that time at $1.1 billion. Pacific Concord retained a 50 per cent interest in the site with a view to a joint re-development. The Tsing Yi site was originally intended to be redeveloped into a residential or industrial complex but the plan was shelved when the much more lucrative possibility of a land swap appeared. As early as last May, when Cheung Kong lifted its stake in Pacific Concord to 17.55 per cent from eight per cent, there was speculation that negotiations over the Ma On Shan land swap deal were about to conclude.