China's biggest mobile carrier looks set to sell Apple's iPhone, hugely increasing the California-based company's distribution in the world's largest smartphone market, the Wall Street Journal reported on Friday.

Apple is preparing to ship iPhones to China Mobile, in a successful conclusion to years of negotiations with the Chinese wireless giant which has some 700 million subscribers, the Journal reported on its website.

The report comes as Apple prepares an event at its headquarters next week where it is expected to unveil two new iPhones, including a cheaper version.

The Journal cited unidentified people with knowledge of the deal as saying that Apple had asked manufacturing partner Foxconn to add China Mobile to its list of carriers to receive a low-cost iPhone.

If confirmed it would finally give Apple access to one of the world's biggest major wireless carriers which does not offer the company's smartphones.

It comes as Apple's sales in China slipped 14 percent from a year ago in the third quarter to $4.6 billion.

Apple has scheduled an announcement in Beijing on Wednesday, a day after its planned event in California.

The development followed reports in Tokyo earlier Friday that Apple has agreed a deal with Japan's biggest mobile carrier, NTT Docomo, to sell its iPhone.

NTT Docomo is in the final stages of negotiations with Apple after losing millions of customers to its domestic rivals, which are way ahead in carrying the handset in Japan, the leading Nikkei business daily reported.

The carrier could start selling the gadget as early as September 20, the Asahi newspaper said.

The Japanese carrier is looking to reverse years of lost business as the iPhone soars in popularity, supplying a big boost for domestic rivals KDDI and SoftBank.

The report comes as Apple itself tries to recapture its own lost market share from South Korean rival Samsung and its Galaxy smartphone, which now dominates the multi-billion-dollar smartphone sector.

Apple's global share of the lucrative smartphone market fell to 14.2 percent in the second quarter, while Samsung's rose to 31.7 percent, according to a survey by US technology research firm Gartner.