A lone gunman used a military assault rifle to fire on a dozen worshipers at an Islamic centre in French-speaking Switzerland late yesterday, injuring one seriously, police said today.

A 23-year-old local man, described by police as a practicing Swiss Muslim, was detained in connection with the attack.

Police had scrambled to intercept a man carrying a weapon openly on the streets of Bussigny-pres-Lausanne near the lakeside city of Lausanne, according to a police statement.

The man entered the centre and fired over a dozen rounds toward a prayer room, police spokesman Jean-Christophe Sauterel said.

"He injured one person seriously before worshipers immobilised him on the ground," police said.

Sauterel said a possible motive for the shooting had not been established and that the man had acted alone. The man used his military weapon and ammunition, police said.

Switzerland's militia system allows soldiers to keep their weapons and ammunition at home, which has become the object of controversy in the wealthy Alpine country following recent attacks and high suicide rates involving military weapons kept at home.

In 2004 in Lausanne, a man wielding a knife attacked a Muslim prayer leader and wounded three others at an Islamic centre. He was not charged for the act after a judge ruled him unable to stand trial due to a psychological disorder.