Police are monitoring “stress” and “growing discontent” within unionist communities over the Irish Sea border.
Assistant Chief Constable Mark McEwan told MPs the health pandemic may be “moderating people’s behaviour in terms of the desire to protest”.
Mr McEwan was giving evidence to the Northern Ireland Affairs Committee.
He added: “Were we not in this current environment we would probably see a more visible outworking of that on the streets.”
He said signs of discontent in the “Protestant, unionist, loyalist community” is being seen in graffiti and on social media platforms.
The Irish Sea border came into effect as a result of the Brexit deal struck between the UK and the EU in December.
Northern Ireland has remained part of the EU’s single market for goods while the rest of the UK has left.
Before the pandemic took hold, the Police Service of Northern Ireland (PSNI) had warned of possible street protests and attempts to disrupt ports.
“We have been engaging with communities to try to monitor that and ensure we have a proportionate response for whatever we might see,” Mr McEwan stated.
DUP North Antrim MP Ian Paisley asked if the PSNI was under-playing things.
He said: “I am worried your comments show a little degree of complacency.
“Are you picking up any sense of the anger and bitterness all sides of unionism feel about this?
“Some sections of the community are starting to sense they are sitting on a powder keg.”
Mr McEwan replied that he was being “considered” in his evidence to the committee.
He said: “I do not want to downplay, or frankly overplay, anything.”
SDLP South Belfast MP Claire Hanna said: “I appreciate you give rational assessments to calm rather than inflame.
“It is important we do not talk up trouble at a very tense and difficult time.”
The Conservative chairman of the committee, Simon Hoare, said it was important the PSNI upheld the Brexit deal.
“Demonstrations, graffiti, violence cannot undermine and overturn the will expressed by the democratically-elected House of Commons.”
Mr McEwan responded by stating the PSNI had a contingency plan to deal with “street protests, disruption at ports and to traffic”.