Wheelock & Co Ltd - a major Hong Kong developer - has started a sale of One HarbourGate East Tower, an unfinished office building it's developing in the city's Hung Hom district that could fetch about HK$4 billion, people with knowledge of the matter said.

Several mainland financial firms have expressed interest in East Tower, which is part of a twin-block office project being developed, the people said, adding that the building could fetch up to HK$16,000 per square foot of gross floor area.

Hong Kong, which boasts the world's most expensive office rents, has attracted mainland companies seeking to boost their brand profiles and diversify their investments. Guangzhou-based Evergrande Real Estate Group Ltd agreed this month to buy an office building in Wan Chai for HK$12.5 billion, breaking previous price records.

East Tower - a 15-story building with about 254,000 square feet of gross floor area - is the smaller block of the twin office towers known as One HarbourGate. Wheelock has said it will sell the development's West Tower to China Life Insurance Co for HK$5.85 billion. The project is expected to be completed by the end of next year. A sale of East Tower could be concluded in the next two to three months, one of the people said.

"We understand from property agents that East Tower attracts great interest in the market," said Wheelock spokesperson Eva Ho.

Wheelock's share price increased 0.14 percent to close at HK$34.6 on Wednesday.

(HK Edition 11/26/2015 page9)