The high-profile loyalist, aged 46, was among two people arrested in a PSNI operation on the Shankhill Road in Belfast on Wednesday morning.
A second 51-year-old man was arrested in the Ballymena area and two suspected firearms were also recovered.
Searches were carried out at a residential property in Ballysillan in north Belfast.
The arrests are believed to be in connection with a hoax bomb alert in March that resulted in Mr Coveney having to flee a peace building event.
In a statement this morning, police confirmed that they have been given more time to question both men.
A PSNI spokesperson said: "Terrorism Investigation Unit Detectives were granted a 14 hour extension for the detention of a 46-year-old male and a 34 hour extension for the detention of a 51 year old male at Belfast Magistrates Court this morning (10th June 2022)."
During the incident in March, loyalist gunmen hijacked a van from a workman in Sydney Street in the Shankill and told him that he would be shot or his family would be injured if he did not do as instructed.
An item, later discovered to be a hoax bomb, was then placed in the man’s van and the victim was ordered to drive it to the Houben Centre on the Crumlin Road, where Minister Coveney was attending a peace event.
The event was organised by the John and Pat Hume Foundation.
Mr Coveney later said of the attack: “I was there to speak about the profound legacy of John and Pat Hume as peacemakers and pioneers of reconciliation.
“What I was there to say that day was that the Good Friday Agreement was achieved by all and belongs to us all.
“That has to mean not just tolerance, but genuine respect and reconciliation”.
Police later said that the hoax bomb was the work of the UVF.
The attack on the event, linked to tensions over the Northern Ireland protocol, was believed to have been sanctioned by the leadership of the UVF.
Two people have already been charged in connection with the incident.
One of the men arrested on Wednesday is well known.
A police spokesperson said: “A 46-year-old male was arrested under the Terrorism Act in the Shankill area. Two suspected firearms have been recovered and a vehicle has been taken away for examination.
“As part of the operation, a 51 year-old male was arrested in the Ballymena area under the Terrorism Act. A van has been seized and taken away for examination.
“Both men are currently being questioned in the Serious Crime Suite of Musgrave police station in Belfast”.