BEIJING -- China's revenue officers are to strengthen the management of income tax collection from people with annual incomes of more than 120,000 yuan (15,000 U.S. dollars), said a senior official with the State Administration of Taxation (SAT).

SAT deputy director Wang Li told a national conference on income tax collection and management that a system should be established to encourage high-income earners to declare personal income voluntarily.

The SAT would concentrate efforts from October and throughout next year on strengthening management and reform of the income tax system and on building a personal income information system to better monitor the actual status of high-income earners.

"There are loopholes in collecting income taxes from this group of people as their sources of income are diverse," said an official with SAT Information Office, who asked to be anonymous.

Personal income tax files should be established and the management of industries with higher revenues should also be highlighted, Wang said.

Meanwhile, he said China's corporate tax revenues rose to 431.6 billion yuan in the first seven months, 29.7 percent or 98.9 billion yuan more than same period last year.

Personal income tax revenues hit 168.4 billion yuan in the period, up 16.4 percent or 23.69 billion yuan, said Wang.

The growth in personal income taxes, introduced by China in 1980, was achieved after the government lifted the personal income tax threshold from 800 to 1,600 yuan a month from January 1.