A number of car recovery companies in Northern Ireland have been warned by dissident republicans that they will be targeted if they continue carrying out work for the police.

It is understood the threats have been issued by the group known as the so-called New IRA.

The PSNI has strongly condemned the threats and said they could jeopardise criminal investigations.

Recovery companies are often used by the police to remove vehicles seized as part of criminal investigations, as well as the scenes of serious accidents.

The vehicles are taken from the scenes of suspected crimes and stored in compounds until examined by the police, or returned to their owners.

Two companies involved in the work have been targeted in arson attacks in recent weeks.

A number of others have been contacted and warned that they will be attacked if they continue their contracts with the PSNI.

Assistant Chief Constable Alan Todd today strongly condemned the threats.

"It’s appalling that nameless faceless individuals have chosen to threaten and intimidate local businesses and disrupt much needed services to communities," he said in a statement to RTÉ News.

"There should be no doubt that targeting contractors in this way has consequences for local people and may jeopardise criminal investigations, for example if a car is used in serious crime can’t be recovered for forensic examination.

"Equally, vehicles left abandoned may become targets for anti-social behaviour, something we know has real-life impact on communities.

"Those behind this vile threat have no support and I am calling on them to withdraw it immediately and explain their actions to the public."

News of the threats comes just a day after an event involving the PSNI in Derry was cancelled because of a protest threat by a party representing dissident republicans.

A youth group in the Bogside area of the city had planned to hold a conference in the Guildhall.

But it was cancelled after the threat by the political party Saoradh, which police say is linked to the so-called New IRA.