HONG KONG (Reuters) - Shares in Hong Kong-listed Chinese property companies surged on Tuesday, after private data showed yearly sales declines for major Chinese property developers continued to narrow in June.

The Hang Seng Mainland Properties Index was up 3.5% by noon, after jumping as much as 4.8% earlier in the session.

Private developers Longfor Group, Shimao Group and Agile each surged more than 5%, while state-backed China Resources Land and privately-owned CIFI Holdings gained more than 4%.

The market is closely watching the impact a major government package of support measures launched in mid-May would have on stabilizing the country's ailing property sector.

Sales value at China's top 100 real estate developers in June rose 36.3% from May, while it dropped 16.7% from a year ago, narrowing from the 33.7% annual decline in the previous month, according to data from property researcher CRIC.

Nearly one-third of these developers, mostly state-owned and state-backed companies including China Overseas Land & Investment, Poly Developments, Greentown China and China Resources Land, posted year-on-year gains in June sales, CRIC said, highlighting the polarization in the sector.

The research firm said it expects more home purchases after the raft of supportive measures, while the yearly drop in July would continue to narrow due to a low base last year.

Another property sector research company, China Index Academy, said on Monday the average price for new homes across 100 cities edged up 0.15% month-on-month in June, their slowest pace in five months.

In May, Chinese authorities unveiled what they called a historic support package for the property sector that has been hit hard by a liquidity crunch since 2021 with many firms defaulting on debt.

(Reporting by Clare Jim; Editing by Rashmi Aich)