The US Air Force and United Launch Alliance have successfully launched the Atlas V 501 rocket into orbit on a secret mission.

The rocket, which is carrying an X-37B space plane, blasted off from Cape Canaveral on Sunday after bad weather delayed the plans for a Saturday launch.

It will be the sixth mission for the solar-powered, crewless plane, which is flown using a remote control.

Also known as an Orbital Test Vehicle (OTV) the aircraft is tasked with deploying a satellite into orbit and testing power-beaming technology but little else is known about the mission as few details have been released by the Pentagon.

The launch of the secretive X-37B was dedicated to frontline coronavirus workers and Americans affected by the pandemic.

 The rocket's payload fairing also featured the words ‘America Strong’ across it.

“We were honoured to partner with the US Space Force to dedicate this mission to first responders, frontline workers, and those affected by COVID-19,” said ULA's Gary Wentz.

"It is truly a unique time in our history and I want to thank the entire team for their continued dedication and focus on mission success."

As a classified programme, the webcast of the launch was required to end early as authorities bid to keep the mission's aims under wraps.

It is understood that the craft is carrying scientific testing equipment and there will be onboard experiments looking at the effects of radiation on seeds and other materials.

Earlier this month, Secretary of the Air Force, Barbara Barrett, said: "This X-37B mission will host more experiments than any other prior mission."

The expected length of the mission is also unknown.