Police formed a human barrier as the demonstrators shouted slogans at each other from a distance of 100 metres at lunchtime on Sunday.
“Our aim is to keep the two groups apart,” police spokesman Niklas Eriksson told news agency TT.
A heavy police presence prevented attempts from both sides to cross the lines just days before construction is scheduled to start on a new mosque at Keillers Park on the island of Hisingen.
Police said the anti-mosque demonstration, headed by known local neo-Nazis affiliated with the Nordisk Ungdom (‘Nordic Youth’) group, consisted of around 100 people. Some 300 people joined the counter-demonstration led by Nätverket Mot Rasism (‘Network Against Racism’), an anti-fascist umbrella group that has come in for stiff criticism for its tolerance of extreme elements.
Police said anti-mosque demonstrators had secured a permit for their rally, which started at midday. Their intention was to march to Lindholmen and the premises of a construction firm set to begin work on the new mosque this Tuesday.