A Housing Authority committee tightened rules on Friday for well-off public housing tenants, raising the likelihood that their rent would more than double.

The new measures, which will be implemented in October, could also see hundreds of well-off households required to move out in four years.

Currently, households that earn two to five times the income limit are paying 1.5 times to double the standard rent.

After the changes, they'd have to pay 2.5 to 4.5 times the normal rate.

Officials said that within a four-year period, if a tenant's income is twice found to be between four to five times the limit, the tenants will have to move out.

As for those who earn five times the limit, the rule remains that they must return the flat immediately.

The chairwoman of the authority's subsidised housing committee, Cleresa Wong, said the government is expected to receive around HK$1.5 billion more a year as a result of the changes.

However, she stressed that the move is not about raising government revenue but about ensuring a fair use of public resources and ensuring all tenants have a similar income-to-rent ratio.

"As a result of this review, generally well-off tenants will now be paying roughly 11 percent of their household income as their rental housing expenses," Wong said after a committee meeting.

"The 'ables' should pay more."

The rental changes, she added, will affect around five percent of public rental tenants, or around 40,000 households.

She also said rules for well-off tenants to buy subsidised flats are also being relaxed.

Those earning four to five times the limit will keep their status as green form applicants for four more years after they'd moved out of public housing.