Security forces in Bahrain opened fire on protesters for a second straight day on Friday, wounding at least 50 people as thousands defied the government and marched towards Pearl Square in an uprising that sought to break the political grip of the Gulf nation''s leaders.

Amateur videos posted on YouTube and accessed by AP Television in London show chanting protesters marching towards what appear to be military vehicles before sustained gunfire erupts.

The first video then shows numbers of injured protesters lying on the ground after the gunfire erupted.

One of the men on the ground is not moving, and there is a pool of blood next to him.

In a brief lull in gunfire, the rest of protesters rush towards the ones on the ground, and then shooting can be heard again.

The second video shows the same incident, but shot within the group of protesters walking towards the army position, who then scatter after the gunfire breaks out.

AP Television could not independently verify the authenticity of the videos.

The clashes on Friday came hours after funeral mourners and worshippers at prayers called for the toppling of the Western-allied monarchy in the tiny island nation that is home to the U.S. Navy''s 5th Fleet, the centrepiece of the Pentagon''s efforts to confront Iranian military influence in the region.

The protesters were calling for the monarchy to give up control over top government posts and all critical decisions and address deep grievances by Shiites, who claim they face systematic discrimination and poverty and are blocked from key roles in public service and the military.