At least 60 dead penguins washed up on Uruguay's coast Sunday in an incident that an environmentalist linked to a fuel spill following a boat crash near Montevideo's port days ago.

Another 34 penguins, covered in oil but alive, also appeared on the beaches of this South American nation's southern coast, Richard Tessore of the Fauna Marina environmental group told local online news outlet Observa.

The dead and soiled birds were Magellanic penguins, which migrate between southern Argentina and the coast of southeast Brazil, Tessore said.

The penguins may have swum through oil spilled when Syros, a Greece-registered boat, and Sea Bird, a vessel registered in Malta, collided near Montevideo last Wednesday. Officials said the collision produced a 13-mile-long (20-kilometer-long) spill near the Rio de la Plata river.

A spokesman for Uruguay's Navy, Marcelo Larrobla, told Observa it was still too early to tell what had killed the penguins.