MEXICO CITY, (Reuters) – Mexico sent 1,000 federal  police and cargo planes loaded with armored cars yesterday to  Michoacan to help quell a flare-up in drug gang violence that  is challenging President Felipe Calderon in his home state.

They join an anti-drug force of several hundred troops and  federal police in the western marijuana-producing state, where  heavily armed traffickers have unleashed a wave of attacks on  security forces in recent days.

One attack on the weekend, apparently in revenge for the  arrest of a high-level trafficker, left the stripped,  blood-smeared bodies of 12 federal police in a heap by a remote  highway — the latest victims of drug gang violence that has  killed some 12,800 people across Mexico since late 2006.