A computer hacker has breached lower-level security at Lawrence Livermore National Laboratory for the 11th time in a week, officials said.

The latest intrusion into the system took place Saturday, the lab announced Monday.So far, the hacker has managed to invade the unclassified research computer systems at the lab at least 11 times during the past week.

There have been no new intrusions since the weekend, Chuck Cole, chief of the nuclear weapons facility, said through a spokesman.