Anyone with a car parked at East Belfast GAA Club should check underneath it, police have warned.
A 54-year-old man has been arrested in connection with three security alerts in east and west Belfast.
The man was detained on suspicion of possessing and making explosives in suspicious circumstances and intimidation.
It follows a search of a residential property in the Braniel area of east Belfast last night, (Thursday 6 August).
The arrest was made as part of an ongoing investigation into a series of incidents, including a security alert at the Henry Jones playing fields on Wednesday evening, (5 August) and two further security alerts in west and east Belfast on Thursday.
The security alerts at Mayfield Square in west Belfast and Dundela Road in east Belfast have now ended.
Three cars, two in east Belfast and one in west Belfast, together with three items that had been placed on them, have been recovered for further forensic analysis.
Chief Superintendent Jonathan Roberts said they believe these incidents, which are being treated as sectarian hate crimes, are linked.
“I am urging anyone who was training with East Belfast GAA club, or anyone else who had a parked vehicle at the playing fields or surrounding area to check on and around their vehicle and report anything suspicious immediately to police.
“I would also ask anyone who was in the area at the time who saw anyone acting suspiciously, or anyone with information which could help our investigation, to contact police on 101 quoting reference number 1693 05/08/20. A report can also be submitted online using the non-emergency reporting form via http://www.psni.police.uk/makeareport/. You can also contact Crimestoppers anonymously on 0800 555 111 or online at http://crimestoppers-uk.org/’ he added.