China Mobile , the country's top cellular phone operator, is planning a multi-billion-dollar share sale in Shanghai as early as next month, sources familiar with the situation said on Monday.

It would likely be the biggest initial public offer of equity in China's domestic markets, exceeding Industrial & Commercial Bank of China's 46.6 billion yuan ($6.1 billion) Shanghai IPO last year, Chinese banking sources said.

China Mobile hired KPMG to audit its proposed Shanghai listing late last year. An auditing report has been completed and submitted in a package of listing documents to regulators in Beijing for consideration, said the source.

"All the necessary documents are well prepared now. The timing of the listing is up to Beijing, but the company definitely aims for as soon as July," said the source.

China Mobile has also hired Goldman Sachs Gaohua Securities to advise on its Shanghai listing, the sources said.

Beijing has selected China Mobile as the first of several major Hong Kong-listed Chinese companies that are expected to list in Shanghai by the end of this year, the sources said.

"We don't have a timeframe for an A-share listing. But that's always been the company's intention," a Hong Kong-based China Mobile spokeswoman said in response to a Reuters inquiry.

Hong Kong's Chinese-language Apple Daily newspaper, citing an unnamed mainland source, said the deal could raise as much as 80 billion yuan. China Mobile shares were up 2.31 percent at HK$77.50 in Hong Kong on Monday morning. (US$=7.626 yuan)