PARIS: Police in southern France arrested 12 people in sweeps against suspected militant networks Tuesday, including three men being checked for potential links to a network recruiting fighters for Afghanistan, officials said. The roundups were part of two entirely different counterterrorism cases under investigation by French judges, and fell on the same day only by coincidence, one police official in Paris said. Firearms were seized in one of the sweeps, another official said. The arrests came as France and many other European nations have stepped up terrorism alert vigilance amid what has been described as an abstract though heightened threat in recent weeks. The US government warned Americans over the weekend to use caution when traveling in Europe. In one of the cases, nine suspected militants were detained in southeastern Marseille and its suburbs, and authorities turned up at least one automatic rifle and a pump gun, the officials said. In Tuesday's other roundup, two men were arrested in Marseille and another in southwestern Bordeaux on suspected ties to a Frenchman arrested in Naples, Italy, last month accused of links to an Afghan recruiting ring.