The unmanned Cygnus cargo vessel, scheduled to arrive Sunday morning at the International Space Station, has been delayed by at least 48 hours due to a software problem, NASA said.

Orbital Sciences Corp, which on Wednesday launched the capsule on an Antares rocket, confirmed that Cygnus had established contact with the space station, but was prevented from continuing approach, the agency said.

The company said it had discovered the origin of the problem and is working on a solution.

Cygnus will dock at the ISS with the help of the station's 57-foot (17-meter) robotic arm, Canadarm2, maneuvered by astronauts on board.

The capsule blasted off Wednesday from Wallops Flight Facility off Virginia's eastern coast, en route to the ISS currently at an altitude of 257 miles (415 kilometers).

Cygnus is carrying some 1,300 pounds (590 kilograms) of goods and equipment including food and clothing for the six-member Expedition 37 crew.

Orbital Sciences has a $1.9 billion contract with NASA that requires the company to deliver freight to the ISS over the course of eight flights by the beginning of 2016.

The company is one of just two private US firms enlisted by NASA to carry payloads to the ISS.

Cygnus will stay docked for a month.