Washington, Aug 13 (DPA) The number of extremist militias are on the rise again in the United States, according to a new report.

Fifty new right-wing militia training groups have formed in the last two years and the gun and ammunition sales have sharply risen, according to the report by the Southern Law and Poverty Centre released late Wednesday.

The militias have traditionally been motivated by their dislike of the federal government, and peaked in national attention in the 1990s following the raid on a sect in Waco, Texas and the 1995 bombing of the federal building in Oklahoma.

The Southern Law and Poverty Centre said extremist crimes are also on the rise, pointing to the shooting at the US Holocaust Memorial Museum in Washington in June. A self-proclaimed Neo-Nazi has been charged in the shooting of the black museum guard.

The report also attributed the rise of militias to a dislike of President Barack Obama. Some conservatives argue that Obama has pursued socialistic policies since taking office.