Nasa has ordered spacewalking repairs to fix a serious computer outage at the International Space Station.

A backup computer for some robotic systems failed on Friday. The main computer is fine and the six-man ISS crew is safe, but the malfunction puts next week's supply run in jeopardy.

Mission managers agreed on Saturday that a spacewalk was needed to replace the bad computer. But officials want one more day before deciding whether the situation is safe enough in orbit to proceed with Monday's SpaceX launch as planned.

Nasa said it would decide on Sunday whether to delay the delivery mission. No date for the spacewalk has been set.

The SpaceX Dragon capsule is loaded with more than two tons of space station supplies at Cape Canaveral. The shipment is already a month late.