UPDATE: Since this story was first published, police has said that a "viable pipe bomb device" was found at the cenotaph in Omagh.
As the police incident ended shortly before 6pm on Remembrance Sunday, Chief Constable George Hamilton said: "This small but potentially dangerous device was left to cause the maximum amount of disruption to the Remembrance Sunday commemorations. This is the action of a small and callous group of violent people who have nothing to offer our communities other than fear and intimidation.
"Whilst our investigation into the incident is at a very early stage one strong line of enquiry is that violent dissident republicans are responsible. Their actions today have demonstrated the disregard and disrespect they have for this community, which has already suffered so much pain and hurt at the hands of terrorists.
"It was a sickening and appalling act on a day which should bring people together to remember the sacrifice made by people from all our communities."
A Remembrance Sunday service in Omagh, Northern Ireland has been disrupted after a "suspicious object" was discovered near a cenotaph. In a statement, local police called the incident a "sickening attempt by cowards to create fear".
The security incident, first reported around 9am, was still ongoing at 11am when the country stood silent and Big Ben chimed. While the event has missed the silence, it's not clear if the ceremony will still take place in some form.
In an initial statement, the Police Service of Northern Ireland (PSNI) said: "Police are continuing to work at the scene of a security alert in the Drumragh Avenue area of Omagh following the discovery of a suspicious object this morning."
Chief Inspector Graham Dodds said: "This is a sickening attempt by cowards to create fear and disruption on a day when many gather to pay their respects to the brave men and women who paid the ultimate sacrifice, and must be unreservedly condemned.
"I would like to reassure the public that we are working hard to make the area safe and that we will continue to provide updates on any impact to today's event."
A later update shared after 11am said the situation was ongoing. "Police are continuing to work with the Royal British Legion and local elected representatives regarding today's event," Dodd added.
DUP MLA Tom Buchanan said: "It is disgusting that anyone would target a war memorial at any time, but on Remembrance Sunday it is an act of particular hatred. The cowardice of those who left this device stands in stark contrast to the bravery of those who are commemorated today."