In pictures: Quebec clashes

There have been more violent demonstrations in the Canadian city of Quebec, where leaders from North and South America agreed that non-democratic nations would be excluded from the world's biggest free-trade zone which they intend to create.

In what appeared to mark a tougher approach, police used water cannon and rubber bullets

The police also used teargas as helicopters hovered overhead

The demonstrators responded, throwing rocks and bottles

Just 300 yards away from the summit venue, protesters began tugging at the fence they had breached before

But while the scenes have been ugly, the numbers involved have been relatively small