SINGAPORE, Dec 3, 2007 (AFP) - Demand for prime office space in Asia's main cities remained strong in the third quarter, despite rising rentals fuelled by strength in regional economies, a real estate consultancy said Monday.

Supply of top grade office space among business districts - especially in Singapore, Hong Kong and Ho Chi Minh City - was limited where the vacancy rate was five percent or lower, said CB Richard Ellis.

"Asian office markets generally sustained their positive momentum in the third quarter of 2007," the Los Angeles-based consultancy said in a report received here.

"Overall demand for office space in Asia's major commercial centres remained robust, with demand from expanding local businesses and non finance related occupiers increasingly significant in many Asian markets," it said.

In Tokyo, average prime office rents rose 6.5 percent from the previous quarter and 20 percent from last year.

Bangkok was the notable exception where demand for office space stayed weak due to the slowing economy and political uncertainty, said CB Richard Ellis.

In Hong Kong, vacancy rates of prime office space in the central area were at historic lows while office rents had soared to new records.

"The effects of high demand were widespread..."

In Manila, rents in the Makati central business district rose 20 percent from the June quarter to an all-time high.

"Given that there are no prime office buildings under construction in Makati, and vacancy is at one percent, rents are expected to continue to increase, prompting some occupiers to consider alternate locations."

Demand was also strong in Jakarta while in Kuala Lumpur, the take-up of new office space was robust.

In Ho Chi Minh City, new office space released into the market are nearly fully occupied and some foreign firms looking to expand their operations have to delay their plans until new supply is available next year.