Police arrested four executives from the Chinese subsidiary of British-based drug maker GlaxoSmithKline on charges they bribed authorities and doctors to boost GSK's sales in the Asian nation, the official Xinhua news agency said Monday.

The suspects, all of them Chinese nationals, include two vice presidents of GSK (China) Investment Co Ltd.

China's Public Security Ministry said last week that several GSK executives had confessed to bribery and violations of tax law.

Payoffs to Chinese public health officials and doctors were disguised as spending on "conference services" and funneled through travel agencies, the ministry said.

Over the course of six years, GSK transferred up to 3 billion yuan ($489 million) to upwards of 700 travel agencies and consultancies, according to the ministry.

GSK offered the bribes "with the objective of expanding the company's market and of increasing the prices of its medicines," the Chinese government said.

The suspects also used false invoices and other maneuvers to diminish the company's tax liability, authorities said.

GSK has six manufacturing plants in China as well as an R&D center in Shanghai, representing an investment of more than $500 million.

The Wall Street Journal reported last month that GSK launched an internal investigation after receiving an anonymous tip about misconduct by the firm's executives in China. EFE