BOGOTA, Colombia (AP) — Colombia is tightening control over its porous border with Venezuela as a growing tide of migrants flees into the neighboring Andean nation.

President Juan Manuel Santos announced Thursday that more than 2,000 additional officers will be dispatched to police the hundreds of dirt-road crossings migrants are using to enter Colombia illegally.

Colombia will also stop issuing border cards that currently allow 1.5 million Venezuelans to temporarily enter the nation to purchase food and medicine.

Santos says Colombia wants to extend its solidarity to needy Venezuelans and will open a migrant attention center capable of providing aid to an estimated 2,000 people. But he stressed that migration to Colombia also needs to be conducted in a safe and legal manner.

Migration authorities estimate 600,000 Venezuelans are in Colombia.