Foxconn Technology Group, the world’s largest custom manufacturer of electronics, resumed hiring at a Chinese factory as it prepares to make a new Apple (Nasdaq: AAPL) iPhone, said a person familiar with the plans.

Workers have been recruited at Foxconn’s plant in Zhengzhou, eastern China, for the past month, ending a hiring freeze imposed in February, said the person, who asked not to be named because the plans haven’t been made public. The extra workers will assemble the new device as well as existing models and have been added at Apple’s request to boost capacity, the person said.

A new iPhone could help Apple regain share amid new smartphone models being released globally this quarter by Samsung Electronics Co. and HTC Corp. Apple, which posted record shipments of iPhones in the December quarter, may post its slowest sales growth since 2009 for the three months ended March 31, according to analyst estimates compiled by Bloomberg.

Foxconn recommenced hiring at Zhengzhou a month ago, with the facility currently employing about 250,000 to 300,000 people, Liu Kun, a spokesman for the Taipei-based company, said by phone today without saying how many employees were added. He declined to comment on products or clients.

Carolyn Wu, a Beijing-based spokeswoman for Apple, declined to comment. Foxconn has hired 10,000 assembly-line workers a week since the end of March, the Wall Street Journal reported earlier today, citing a person at the company it didn’t identify.

Hon Hai Precision Industry Co., the Taipei-listed flagship of Foxconn, makes iPhones in Zhengzhou, Shenzhen and Taiyuan as well as Jundiai, Brazil, according to an Apple supplier list published in January. IPhones are the only Apple product assembled in Zhengzhou, while Taipei-based Pegatron Corp. also makes iPhones in Shanghai, the list shows.

Apple sold a record 47.8 million iPhones in the fiscal first quarter of 2013, which ended Dec. 29, after releasing its iPhone 5 in the prior quarter. Sales probably climbed 8.8 percent to $42.6 billion in the fiscal second quarter, the slowest since September 2009, according to the average of 42 analyst estimates compiled by Bloomberg.

Hon Hai’s quarterly sales dropped the most in at least 13 years as computer and electronics sales slow, according to revenue data released April 10.

Samsung, the world’s largest smartphone vendor, will release its Galaxy S4 for sale in the U.S. April 26, while the HTC One will be offered in North America, Europe and Asia by April 30.

Apple, which overtook BlackBerry and Nokia Oyj to become the world’s largest smartphone maker, ceded top spot to Samsung last year as the South Korean company’s Galaxy models climbed in a market that Bloomberg Industries said had $294 billion in sales.