U.S. aviation regulators said on Thursday they would permit Boeing Co to conduct test flights of its 787 Dreamliners, which have been grounded since January after two battery related safety incidents in a matter of days.

"The primary purpose of the test flights will be to collect data about the battery and electrical system performance while the aircraft is airborne," said a statement from U.S. Transportation Secretary Ray LaHood and Michael Huerta, the head of the Federal Aviation Administration.

The test flights will be subject to a number of restrictions. It was unclear when the testing program would start.