Washington, Aug 18 - Within a week, yet another man showed up with an assault rifle outside the venue of President Barack Obama's meetings, raising concerns about the safety of the first black president in US history.

Obama reportedly faces about 30 potential death threats every day, according to reports earlier this month.

With his rifle slung over his shoulder, the man was seen among protesters outside the venue in Phoenix in Arizona where Obama was addressing the Veterans of Foreign Wars Monday.

According to local media outlets who identified the man as Chris, he was also carrying a pistol holstered at his side.

The man could be seen arguing heatedly with those rallying in support of Obama's heath-care reform plan, reports said.

But Phoenix police said its plainclothes detectives kept a watch on the man who broke no law under Second Amendment rights.

Arizona is an 'open-carry' state, legally allowing people to carry a firearm in public so long as it is visible to others. However, a permit is required to carry the weapon which is concealed.

This is the second such incident within a few days at the meetings addressed by Obama.

Last week, a protester was seen carrying a gun strapped to his thigh outside a town hall meeting addressed by Obama in New Hampshire state which also allows people to carry weapons openly.