French prosecutors want activists who bared their breasts in Notre Dame Cathedral to pay thousands of euros in fines for damages.

Nine activists from feminist group Femen pounded a huge church bell in the landmark Paris cathedral in February 2013 to express anger at the Catholic Church’s opposition to gay marriage, and to “celebrate” the resignation of Pope Benedict XVI.

The activists, wearing T-shirts and garlands of flowers, went on trial in Paris on Wednesday. The prosecutor requested fines of 1,500 euros($A2,250) against each activist for charges of damaging property.

Also on trial were Notre Dame guards who pulled the activists off the bell, accused of acts of violence. The prosecutor requested suspended fines against the guards.

A verdict will be issued on September 10.