Office property prices have risen 10 to 15 per cent since the start of the year and are expected to grow a further 5 to 10 per cent in the short term, according to Colvin & Horne. The company said many recent office transactions were related to properties with tenancy agreements, which indicated the confidence of long-term investors. For instance, about 3,000 square feet of office space on the 17th floor at Convention Plaza in Wan Chai were sold for $12,300 per sq ft along with a lease, due to expire in October 1998. Despite a relatively low rental yield of 5 per cent, the company said the office sales market remained optimistic because the number of quality offices available for sale was limited. According to Colvin & Horne, the office sales market was active, especially in Central, Admiralty and Wan Chai. It estimated that grade A office transactions on Hong Kong Island amounted to $1.44 billion, accounting for about 55 per cent of the volume in the territory. There were 119 office transactions worth $2.6 billion last month. In Tsim Sha Tsui, there were 34 transactions worth $453.9 million. Spaces at Lippo Centre were the most actively traded properties, with about 52,000 sq ft worth $450 million changing hands. Average transacted prices were about $8,700 per sq ft. Offices in Nine Queen's Road Central were traded at about $12,000 per sq ft while those in Bank of America Tower were sold for $9,200 per sq ft. The consultants said in addition to three floors in Nine Queen's Road Central bought by Singapore companies, a local investor had recently paid $10,600 per sq ft for the 24th floor. Smaller office units in the building were also in demand. It said a 3,000 sq ft unit on the 16th floor was sold for $11,800 per sq ft while a 1,800 sq ft unit with a sea view was sold for more than $13,000 per sq ft. It said a company had bought a 1,600 sq ft unit in Worldwide House for $8,800 per sq ft and was now seeking $9,600 per sq ft for it. Lippo Centre, a popular site in Admiralty, saw about 72,000 sq ft of office space worth more than $627 million in April and last month, the firm said. Among the transactions, a 3,000 sq ft unit on the fifth floor in the centre's Peregrine Tower was sold to a China-funded company for $7,500 per sq ft. A local investor bought a 2,000 sq ft unit on the 36th floor for $9,360 per sq ft earlier and was now trying to sell it at $10,000 per sq ft.