Hong Kong stocks booked modest gains on Thursday after Beijing revealed measures to support the economy as the US Fed kept interest rates steady.

The Hang Seng Index jumped 0.37%, or 84.04 points, to end at 22,775.92. The Hang Seng China Enterprises Index climbed 0.7%, or 58.00 points, to 8,300.25.

Chinese officials said Thursday they would support the private sector through a recently-passed law taking effect May 20, the South China Morning Post (SCMP) reported.

China's vice-minister of justice, Wang Zhenjiang, said the law has defined the private sector's legal status and the government's support for it for the first time, according to the SCMP report.

Elsewhere, the US Federal Reserve kept its interest rate unchanged in the 4.25% to 4.5% range, with Chair Jerome Powell expressing uncertainty on the direction the US economy will take amid Washington's tariff policy, Reuters reported.

Mimicking the move, the Hong Kong Monetary Authority also left its base rate steady at 4.75%.

In corporate news, two firms marked their Hong Kong debut on Thursday.

Photovoltaic cell manufacturer Hainan Drinda New Energy Technology (HKG:2865, SHE:002865) closed at HK$26.60, 20% higher than its IPO price of HK$22.15.

Bubble tea chain operator Auntea Jenny (Shanghai) Industrial (HKG:2589) soared 40% at the closing bell to end at HK$158.40, compared with its IPO price of HK$113.12.