Beijing is ramping up its efforts to identify "naked officials" -- those whose relatives have moved abroad -- reports said Tuesday, as part of a high-publicised anti-graft crackdown.

At least 10 Chinese provinces have launched investigations to track down so-called "naked officials", the Southern Metropolis Daily newspaper reported.

They include south China's Guangdong province and neighbouring Fujian province, both regions with a long history of migration.

The term "naked official" refers to a government employee whose immediate family members have acquired citizenship or permanent residency overseas, potentially allowing them to spirit ill-gained wealth out of the country.

Since 1990, about 18,000 corrupt officials have fled China with a total of more than $120 billion, according to a 2011 report by the People's Bank of China.

Many of them used family members to stash their funds beyond China's borders.

According to the Southern Metropolis Daily report, the ruling Communist Party's Central Organisation Department has called for "naked officials" to be barred from holding key positions in the central and provincial government.

Some provinces have launched internal campaigns to "thoroughly study and analyse the problem", it added.

Last month, Guangdong province took action against 866 "naked officials", who were transferred or forced into early retirement, the state-run China Daily newspaper reported.

Chinese President Xi Jinping took office last year vowing to root out corrupt officials, warning that graft could destroy the party.

Corruption causes widespread public anger and the drive has been widely touted.

But critics say no systemic reforms have been introduced to combat it, while citizen activists calling for such measures have been jailed on public order offences.