Mexico’s government has acknowledged that at least two well-known Mayan ruin sites are unreachable by visitors because of a toxic mix of cartel violence and land disputes.

But two tourist guides in the southern state of Chiapas, near the border with Guatemala, say two other sites that the government claims are still open to visitors can only be reached by passing though drug gang checkpoints.

The explosion of drug cartel violence in Chiapas since last year has left the Yaxchilán ruin site completely cut off, the government conceded Friday.