German police used water cannons and pepper spray to disperse G-20 protesters

Thomson Reuters

German riot police use water cannons against protesters during the demonstrations during the G20 summit in Hamburg

German police have used water cannons and pepper spray to disperse protesters in Hamburg after being attacked with bottles and stones by some marchers protesting the Group of 20 summit.

Police say they repeatedly asked a group of hardcore anti-capitalist demonstrators to remove their masks Thursday evening, to no avail. They then decided to separate the group from the rest of the several thousand-strong demonstration.

Black-hooded protesters attacked a police vehicle with bottles and bricks, breaking its window.

The violence broke out near the start of the demonstration - titled "G-20: Welcome to Hell" - at a riverside plaza used for Hamburg's weekly fish market.

More than 100,000 protesters are expected in Hamburg for the summit, which takes place Friday and Saturday. German authorities said Tuesday they believe around 8,000 were prepared to use violence.

Roughly 20,000 police officers will deployed throughout the summit. Authorities will also be using drones - both aerial and underwater - as they seek to keep tabs on expected protests.

Here are some images from the clash: