Disturbance by individuals who use violence to oppose Northern Ireland's place in the United Kingdom could be an attempt to draw officers into gun or bomb attacks, the BBC cited Chief Constable Simon Byrne as saying in a public briefing.

The PSNI has made temporary changes to work shifts to put more officers onto frontline duties, he said.

Assistant Chief Constable Bobby Singleton said the PSNI had "very strong community intelligence" that attacks were being planned in Londonderry, a city near the border with the Republic of Ireland, the BBC reported.

The Police warning comes ahead of President Biden's visit next week and after British intelligence agency MI5 increased the threat level from domestic terrorism in Northern Ireland to "severe".

There is sporadic violence in Northern Ireland by small groups that has kept the threat level mostly at "severe" since the system was introduced in 2010.

In February, Detective Chief Inspector John Caldwell was shot a number of times by two gunmen, an attack the police suspected was carried out by the New Irish Republican Army (New IRA) militant group which seeks to merge Northern Ireland with the Republic of Ireland.

(Reporting by Rahat Sandhu and Shivani Tanna in Bengaluru; Editing by Christopher Cushing)