Steve Jobs, chief executive of Apple, said that the suicide rate at the Chinese factory – where 12 of the company's 400,000 employees have killed themselves this year – was lower than the overall suicide rate for the United States.

According to the World Health Organisation, the average annual suicide rate in the United States is 11.1 people per 100,000 of the population. The most recent statistics available date from 2005.

The factory makes components for many of Apple's products, and has been criticised in some quarters for the way it runs its business.

Jobs said Apple was "on top" of the situation, and that the company took its corporate and social responsibilities seriously.

"We are all over this," he told delegates at the D8 technology conference in California. "We look at everything at these companies, and I can tell you a few things that we know: Foxconn is not a sweatshop.

"It's a factory, but they have restaurants and movie theatres. They've had some suicides and attempted suicides. They have 400,000 people there. The rate is under what the US rate is, but it's still troubling."

Jobs said that there had been a spate of copycat suicides in Palo Alto, his hometown, and that Apple was working hard to get to the root of problems at Foxconn. "We're trying to understand this, we have people over there," he told delegates.