US stocks closed mostly lower on Thursday, with the biggest drag from Apple and weakness in chip stocks over concerns about China's iPhone curbs, while a fall in weekly US jobless claims fed worries about interest rates and inflation.

Shares in S&P heavyweight Apple fell for a second straight day on news that China had widened curbs on iPhone use by state employees, requiring staff at some central government agencies to stop using their mobiles at work.

The S&P 500 lost 0.3 percent to 4,453, the Nasdaq Composite lost 0.9 percent to 13,748. The Dow Jones Industrial Average rose 0.2 percent to 34,500.

The Dow outperformed the S&P and Nasdaq because Apple ranks just 11th in the index, which is price-weighted compared with the market capitalization-weighted S&P 500, where Apple is one of the biggest components.

A US Labor Department report showed the number of Americans filing for unemployment claims fell to 216,000 for the week ended September 2, hitting the lowest level since February. But investors worried this could encourage the Federal Reserve to continue with tight monetary policy, pressuring stocks.

"The weekly claims was big news this morning, good news being construed as bad news and it's hard to ignore the news out of China," about Apple said Sahak Manuelian, managing director and head of equity trading at Wedbush Securities.

Investors were also warily anticipating inflation readings from August, due out in a week.

"There is that very, very small eye of the needle with which the Fed can thread monetary policy that's sufficiently tight, but not so tight that it wrecks the economy. It's a small eye but, it's not completely closed," said said Craig Fehr, head of investment strategy at Edward Jones, who called Thursday's decline "a cautious defensive stance."

The Philadelphia semiconductor index fell while shares of Apple suppliers including Skyworks Solutions, Qualcomm and Qorvo were in the red all day.

Rick Meckler, partner at Cherry Lane Investments said the news from China refocused investors on the idea "that the relationship between the US and China is a big risk to current equity prices, particularly in technology."

Also denting sentiment about the world's second-largest economy, data showed China's exports and imports fell in August. (Reuters)