The US Federal Aviation Administration (FAA) has raised the limit of the altitude authorisation for unmanned aircraft systems (UAS) to 400ft.
The limit has been raised for Section 333 exemption holders and government aircraft operators, after the FAA conducted a comprehensive risk analysis.
The US federal agency had previously set a nationwide Certificate of Waiver or Authorisation (COA) for UAS flights up to 200ft.
The new COA policy allows smalls drones, with the exception of those used for commercial purposes, to fly to a maximum height of 400ft.
Under the new move, the FAA will allow the drones to fly at or below 400ft for UAS operators, with a Section 333 exemption for aircraft weighing less than 55lb and for government UAS operations.
The small UAS can travel anywhere in the US except certain restricted airspaces, including major cities where the FAA does not allow UAS operations.
FAA Administrator Michael Huerta said: "This is another milestone in our effort to change the traditional speed of government.
"Expanding the authorised airspace for these operations means government and industry can carry out unmanned aircraft missions more quickly and with less red tape."
According to FAA, this new service will help reduce the workload for COA applications for the agency's Air Traffic Organisation, as well as for industry UAS operators and other government agencies.
The step taken by FAA will also be able to reduce the requirement for individual COAs by 30-40%.
UAS operators can fly their drones under daytime visual flight rules, keeping the UAS within sight of the pilot and maintaining certain predefined distances from airports or heliports.
The aircraft have to maintain a distance of 5nm from an airport with an operational control tower; 3nm from an airport that has a published instrument flight procedure, but not an operational tower; and 2nm from an airport that has neither a published instrument flight procedure nor an operational tower.
A distance of 2nm has to be maintained from a heliport with a published instrument flight procedure.