Twenty-five Muslim headstones have been desecrated in an attack being treated by police as racially-motivated.
Police are supporting affected families
Gwent Police are investigating the incident at St Woolos Church, Newport.
Police said the headstones in the Muslim area of the graveyard were pushed over on Friday morning, causing "considerable structural damage".
Officers have stepped up patrols in the area and are contacting relatives. They are also speaking to community leaders to address any possible wider issues.
The force crime prevention and schools liaison officers will also be working with local schools.
Scenes of crime officers have attended the churchyard to gather photographic evidence as part of the inquiry.
Gwent Police diversity officer Pc Molly Williams is working with the church to contact relatives of the deceased.
"The incident is being treated as racially-motivated at this time as only Muslim graves were desecrated," a police spokesman said.
"However, due to the layout of the site - the section is hidden by large bushes making it secluded - other lines of enquiry are being pursued."
Chief Inspector Dave Johnson said: "Newport Police are committed to protecting all members of the community and this act of vandalism appears to be aimed at our Muslim community.
"We are determined to carry out a full and thorough investigation and appeal to members of the public to come forward with any information so we can bring the perpetrators to justice.
"We cannot begin to understand the impact on the families and we will work with them through our diversity officer to offer support while we carry out the investigation."
Anyone with information contact police on 01633 838111 or anonymously on Crimestoppers 0800 555111.