German police have used water cannons and tear gas as they faced off against thousands of protesters outside the site of the Group of Eight summit in the northern German Baltic Sea resort of Heiligendamm.
Police said they resorted to the measures after protesters began pelting officers with stones. At least eight officers were injured.
By late afternoon Wednesday, authorities said protesters had blocked all three main roads leading from the local airport to the nearby summit site. But authorities later cleared at least one of the roads.
In a related development, Germany's Constitutional Court upheld a lower court ban on protests planned for Thursday outside the 12 kilometer-long security fence surrounding Heiligendamm. However, some protesters already had reached the site by the time the ruling was issued.
Thousands of protesters backing a wide range of leftist causes are gathered near the summit site. Sixteen-thousand police are guarding the fence topped with barbed wire that encloses the summit site.