Boeing is widening inspections of 787 Dreamliners following the discovery of component manufacturing defects.

The company said it was implementing more stringent measures to catch defects - which it thought were already resolved and confined to the jet's rear fuselage only.

Inspectors discovered unacceptable tolerances in some components delivered to its U.S. assembly facilities, it said.

Boeing asked inspectors to review factories in South Carolina and Kansas along with fuselage component plants jointly owned by Leonardo in Italy and Kawasaki in Japan. The company said inspections were underway for all undelivered 787 jets at its final assembly plants in North Charleston and Everett.

"Boeing discovered that some areas of the 787 circumferential fuselage join may not meet specified skin flatness tolerances. We are working with suppliers to make sure inspections happen and that rework is done as needed," Boeing representative Jessica Kowal said.

The Federal Aviation Administration said in a statement it was working with Boeing to "oversee the safety of the planes" and to "review its manufacturing oversight."

The expanded inspections of the 787 Dreamliner and its components are expected to delay deliveries. A report published by The Wall Street Journal on Tuesday said Boeing halted all deliveries of its 787 Dreamliners after it discovered flaws in November.

Boeing chief financial officer Greg Smith said the company still had many undelivered 787 jets. He said the company hadn't made any 787 deliveries in November.