Like their US counterparts, the Mexican authorities have been cracking down on illegal immigration in recent weeks. In mid-August, a joint operation comprising federal and state police officials, as well as military personnel, was launched in the southern state of Tabasco, bordering Guatemala.

The aim of the operation was to locate and repatriate illegal immigrants, many of whom travel from other Central American countries and pass through Tabasco on their way to their final destination: Mexico's northern border with the US. The operation was partially successful; 350 illegal immigrants were deported and a further 144 were detained by the police.

The figure of 350 repatriations is somewhat low, given that Tabasco has become an immigration bottleneck since late July. On 29 July, the rail company Genesee & Wyoming ceased services on its route from Chiapas to Mayab, which is the nearest northbound rail link running from near the Guatemalan border. Traditionally, illegal immigrants have used trains as a means of traversing Mexico's hostile southern terrain, either by picking up the link directly from Chiapas state (which also borders Guatemala) or from Tabasco.

However, the train closure has left hundreds of immigrants stranded in Tabasco and surrounding states, with local organisations estimating the transient immigrant population to up to 6,000 people. While these immigrants usually spend only a few days in Tabasco, an increasing static population is generating local concerns regarding increased crime. Local cross-border people smuggling networks have benefitted, since immigrants have now lost one of their primary means of crossing Mexico independently. Instead, they will have to rely on people smugglers to arrange their passage to the US border, if they can afford it. Those who do not have the funds will be forced to remain in the southern states until a new transport route opens up - either by walking over 300 miles to the Coatzacoalcos rail link or hoping the Chiapas-Mayab link reopens in 2008.