By Kamal Namaa FALLUJA, Iraq (Reuters) - Islamist militants stormed police stations in several cities of Iraq's western province of Anbar on Wednesday, seizing weapon caches and freeing prisoners after security forces dismantled a Sunni Muslim protest camp on Monday. The attacks on three police stations in Falluja, Ramadi and Tarmiya represent a serious escalation in the confrontation between Iraqi Sunni groups and the Shi'ite-led government of Prime Minister Nuri al-Maliki.