Mexico has introduced new rules limiting the number of foreign human rights observers allowed to visit the country, in an attempt to curb what President Ernesto Zedillo has called revolutionary tourism.

The move follows a controversial visit earlier this month by more than one-hundred Italians to the troubled state of Chiapas.

The group was accused of violating Mexican law which forbids foreign involvement in national politics.

Under the new regulations, visiting groups are limited to ten people, and a stay of ten days.

Observers must also apply for a special visa thirty days in advance.

Human rights groups say the restrictions could hamper their work.