CHIEF Constable Simon Byrne has said there was "no credible intelligence" to substantiate any threats to workers at Larne or Belfast ports.
Mid and East Antrim Borough Council last week withdrew workers from Larne over security concerns, before returning later in the week.
It followed the appearance of threatening graffiti linked to Brexit checks and claims that car registrations had been recorded.
Physical checks were also temporarily suspended on most goods by the Department of Agriculture, Environment and Rural Affairs (DAERA) at both Larne and Belfast.
The decision was taken by minister Edwin Poots in one of his last acts before he temporarily stepped down to receive treatment for cancer.
Speaking to The Irish News, Mr Byrne said: "I think we have to recognise firstly that emotions are running high and there are political perspectives on the consequences of that.
"But the events of the start of the week were particularly unhelpful because there was no credible intelligence to substantiate any threats to people working in either Belfast or Larne ports.
"We have worked hard... to convince people of that and to get people back to work.
"There have been numerous issues of graffiti across the country and we've actually made a number of arrests for that."
Mr Byrne added: "At the moment I'd re-assure people that whilst our antenna are up, there is no credible intelligence about attacks or threats to port workers."
In the assembly yesterday, Sinn Féin's John O'Dowd claimed the danger to staff was "non-existent".
"The information given to this assembly and to Mid and East Antrim council was based on half-truths, misinformation and erroneous information," he said.
During questions to new agriculture minister Gordon Lyons, the Upper Bann MLA added: "Workers were used as pawns in a very, very cruel game."
"I've no problem with anyone ensuring the safety of their workers but my concern is this, the fact that there is no credible threat which has been stated by the PSNI and the fact that a lie got halfway around the world before the truth had got its pants on," he said.
"That that agenda of those workers being removed, suits your political agenda and rather than dealing with the facts, you're allowing these non-existent threats to carry forward a political agenda which would be contrary to your statutory duty and the code which you have as a minister."
Mr Lyons said it was a "disgraceful" assertion.
"I have very clearly demonstrated staff safety comes first."
He said a process had been put in place which he had not interfered with and his department was in discussions with police and workers' unions.
"I find that an entirely appropriate response to what has gone on."
He added: "It is important that we take precautions and we put the safety and wellbeing of our staff first and foremost and that is what we have done."
