FERGUSON (AFP) - President Barack Obama has ordered an investigation into whether it is "appropriate" for the US military to sell battle-grade hardware to local police, a senior US official said on Saturday.

The order follows widespread criticism of local authorities' use of military gear in Ferguson, Missouri after the fatal shooting of an unarmed black teenager by a white police officer. Police there met protests with a massive show force - body armour-clad officers perched on armoured trucks toting stun grenades and assault rifles - thanks to their access to such US military hardware.

Obama "has directed a review of federal programs and funding that enable state and local law enforcement to purchase military equipment."

The review will consider "whether these programs are appropriate," whether training with the equipment is sufficient, and whether there is enough federal oversight of the gear's use.

The investigation will be headed by "White House staff including the Domestic Policy Council, the National Security Council, the Office of Management and Budget," the official added.

The funeral of teenager Michael Brown, set to take place on Monday, is likely to be a focal point for more demonstrations by angry protesters demanding that Darren Wilson, who shot the teenager at least six times, face justice. The demonstrations, at times violent, have stretched on for two weeks.