BERN, Sept 21 (Reuters) - Between 300 and 400 protesters occupied a square near the Swiss National Bank in Bern on Monday, as leaders of the group that has also targeted banks including Credit Suisse said they were seeking to highlight inaction on climate change.

A spokeswoman for the protesters, from various environmental campaign organisations, said they were building a camp near the Swiss parliament to highlight demands to reduce net emissions to zero by 2030. About 40 protesters chained themselves to objects or to each other to prevent them from being removed easily by police, should authorities object to the protest, a Reuters witness said. (Reporting by Denis Balibouse, writing by John Miller)