Right- and left-wing extremists clashed overnight in the northern German port city of Rostock, injuring 14 police officers, according to local police.

Clashes erupted during the night when a shop frequented by right-wing extremists was attacked, Rostock police said in a statement, adding that the shop is often targeted by left-wing extremists.

"The police arrested 40 people from the right- and left-wing spectrum," said the statement.

The arrested have been accused of disturbing the peace, causing bodily harm, damaging property and other crimes, the statement noted.

When police tried to prevent a violent clash between the two groups, they were attacked by about 150 leftists with stones and bottles, the statement said.

About 200 police officers rushed to the spot shortly before midnight Saturday when a large group of left wingers was seen moving to the shop.

Rostock was the scene where thousands of anti-G8 demonstrators gathered to protest before and during a summit of the Group of Eight rich nations in nearby Heiligendamm earlier this month.