The PSNI is to review policing arrangements in Greysteel, Co Derry after a bus carrying Orange Order members from Donegal was stoned.
A window on the bus was broken and one person suffered minor injuries.
The Orangemen from Manorcunningham and Newtowncunningham were returning home on Monday evening.
DUP MP Gregory Campbell said he alerted police to concerns a short time before the attack.
“I was returning from Coleraine just before 5.30pm and noticed that no police officers appeared to be in the vicinity where they are usually deployed. I immediately rang a senior police officer who said my information would be passed on.”
Mr Campbell said that while responsibility lay with those who threw stones, police should explain their approach given that buses have been attacked in Greysteel in the past.
A police spokesman said an investigation was underway to identify those behind the attack.
He added: “Police will review the incident at Greysteel and address any issues that are identified accordingly.”
Sinn Fein councillor Dermot Nicholl said those involved had nothing to offer society.
SDLP MLA John Dallat said they "represent no-one and should be thoroughly ashamed of themselves".
