Security forces were attacked with petrol bombs during overnight violence in Derry, a PSNI spokesman said today.
Most of the trouble took place around the fringes of the Fountain area, a small Protestant enclave in the city.
At least 14 petrol bombs were thrown during the disturbances, but there were no reports of any injuries, the PSNI reported.
The violence followed smaller disturbances in Derry earlier in the week.
Later this month the annual march by the Apprentice Boys takes place in one of the last major events of the marching season.
The Apprentice Boys parade has passed off peacefully in recent years, but tensions have been raised by violence at an Orange Order march in Belfast last month.
