Google Inc's Gmail was blocked in China after months of disruptions to the world's biggest email service, with an anti-censorship advocate suggesting the Great Firewall was to blame.

Large numbers of Gmail Web addresses were cut off in China on Friday, said GreatFire.org, a China-based freedom of speech advocacy group. Users said the service was still down on Monday.

"I think the government is just trying to further eliminate Google's presence in China and even weaken its market overseas," said a member of GreatFire.org, who uses a pseudonym.