* New home sales in Beijing rose 16.9% in Sept. 4-10 week -survey

* Suggest steps to revive property market having some impact

* But rebound not reflected across China

* Many potential homebuyers waiting for more policy measures

BEIJING/HONG KONG, Sept 11 (Reuters) - New home sales in Beijing jumped last week, keeping property showrooms open late into the night to meet demand, in a sign government efforts to revive the sector are yielding some results in the Chinese capital if not elsewhere in the country.

A survey by real estate research firm China Index Academy showed on Monday new homes transactions in Beijing rose 16.9% by area sold in the week of Sept. 4-10 from the previous week even as they fell 20% on average across the country.

Another report, by Haitong Securities, showed sales by area in China's four largest cities were still down 45% in the first week of September from the same period last year.

The figures suggest that China's latest steps to revive a crisis-hit property market, including lower mortgage rates and down payments, could unlock some pockets of housing demand in the most sought-after areas, but may struggle to halt the broader property market downturn.

"These measures may generate a short-term rebound in property transactions, but are insufficient to stabilize the property market," Goldman Sachs analysts said in a note.

Beijing and other big cities said more than a week ago they will allow people who have fully repaid their previous mortgage or sold their other homes to make down payments of as little as 35-40%, compared with 60-70% previously.

This prompted interested buyers such as 75-year-old Zhang Guoqiang to rush to property showrooms across the capital.

"I'm worried that if I don't buy soon, there won't be any good flats left," said Zhang, as he visited a development by state-owned CR Land in northern Beijing with his wife and daughter.

"I'll put my small, old apartment for sale as soon as I get home."

Real estate agents were trying to sell the remaining 10% of the project's total of 1,000 apartments, keeping doors open for potential buyers until 10:30 p.m. (1430 GMT) over the weekend, three hours longer than initially planned.

"Customer traffic has definitely increased significantly since the new policies came out," agent Zhao Jie said. "I worked until 2.00 am on the first day after the announcement and sold 10 flats that night."

MORE RADICAL POLICIES EYED

At another Beijing project by private developer Longfor Group, agents said visits by potential buyers more than doubled in the past week. They were mostly people who looked to sell their old homes either in Beijing or in other cities in China and replace them with new ones, the agents said.

But Yu Fei, a property sales agent at HomeLink, said the initial spike in interest he noticed in the first few days is already petering out.

"Many homebuyers remain in a wait-and-see approach, some hoping for more radical policies to stimulate the property market," Yu said.

Goldman analysts said if property sales kept sliding policymakers could release more liquidity into the market by cutting banks' reserve requirement ratios, lowering rates, easing home purchasing rules further.

At the CR Land project, a visitor surnamed Wan, who spoke on condition of partial anonymity for privacy reasons, said he was inclined to keep searching for cheaper apartments. At the same time, he was worried that prices might rise beyond reach should further easing measures be introduced.

"I'm still hesitant," Wan said.

(Editing by Emelia Sithole-Matarise)