LIMA, Peru (Reuters) - Colombian President Andres Pastrana said on Saturday he is worried that FARC guerrillas may be crossing into Venezuela, from where his government alleges they launched an attack on Colombia this week. "Yes, logically we are worried," Pastrana told reporters in Lima in answer to a question about the attack, in which 38 Colombian troops and rebels from the Revolutionary Armed Forces of Colombia, or FARC, died in clashes. It was the heaviest death toll in an attack since peace talks with the Colombian Marxist rebels collapsed last month. Venezuela said on Friday it was "insulted" by...