China will begin conducting spot checks this year on assets and other personal information reported by officials to the ruling Communist Party and punish those with hidden wealth, state media reported.

The internal declarations are not made public, and in the past a lack of oversight had largely reduced the system to a formality.

However, the government has faced increased public pressure to improve transparency around officials' wealth, following a wave of scandals involving assets ranging from luxury watches to houses.

The party's internal income declaration system for dates back to 1995, and officials have been required to submit a broader range of information including personal income, family assets and relatives' emigration records for the past three years.

This year, the party's powerful organisation and personnel departments will conduct random sampling of the information submitted, to check if it is truthful and complete, the official Xinhua news agency said late on Thursday.

They will also pay closer attention to the declarations submitted by officials set for promotion, Xinhua added.

Routine declarations for this year will be submitted in January. Officials who do not report on time or truthfully will face punishments including sacking, Xinhua said.

"The most prominent feature of this declaration is that it reflects a strict administering of the party and officials," Xinhua cited an unnamed official as saying.

With the exception of a few pilot programmes, the party has shown little interest in wanting to set up a nationwide system to publicly disclose officials' wealth, and instead has arrested several activists who urged this.

President Xi Jinping has launched a sweeping crackdown on corruption since taking power, vowing to pursue high-flying "tigers" as well as lowly "flies", saying graft is so serious it could threaten the party's very survival.