TOKYO — Japan’s space agency said on Friday that information on one of its newest rockets was stolen from a desktop computer by someone using a computer virus.

The Japan Aerospace Exploration Agency said that the virus in a computer at its Tsukuba Space Center northeast of Tokyo was found to be secretly collecting data and sending it outside the agency. The agency said that after the virus was detected by antivirus software on Nov. 21, it conducted an emergency sweep for viruses that showed no other computers at the center had been infected.

The agency said it was unclear if the virus was a cyberattack. Japanese defense companies, however, have been recent targets of similar information-stealing viruses, some previously traced to China.

The data stolen from the space agency included information about the Epsilon, a solid-fuel rocket still under development. While the Epsilon is intended to launch satellite and space probes, solid-fuel rockets of that size can also have a military use as intercontinental ballistic missiles.