Demonstrators have been battling heavily outnumbered police in violence in Gothenburg, Sweden as European Union leaders meet for a summit.

At least two shooting victims have been admitted to hospital, said a hospital spokeswoman. Reuters news agency reported that police were forced to retreat before a crowd of roughly 1,500 protesters, abandoning vehicles near the city's university - less than a mile from the conference centre where the 15 EU leaders are meeting. Swedish radio warned people to stay away from the city centre due to the violence on a day when more than 600 people were detained during 12 hours of rioting. The severity of the demonstrations prompted police to relocate a planned dinner for EU leaders. Police decided the dinner, originally to be held at the elegant Tragar'n restaurant in the city's Botanical Gardens, would instead be held in the conference centre, which is guarded by hundreds of police. Four delegations attending the summit were also asked to change hotels after police said they could no longer guarantee their safety from protesters, a spokesman for the Finnish delegation told AFP. Shops were looted and buildings damaged some distance away from the meeting, where EU leaders discussed ways of putting expansion plans back on track after Irish voters rejected them.