Frontline police officers caught up in this summer's violence on the streets of Belfast are undergoing psychiatric treatment, it has been revealed.
Police Federation chairman Terry Spence said significant numbers needed specialist care after months of bombardment with petrol bombs and other missiles.
He warned that more than 500 Police Service of Northern Ireland (PSNI) officers had been hurt since last summer because of trouble surrounding loyalist parades and protests over restrictions on the flying of the Union flag from the City Hall.
Mr Spence said: "Officers are working around the clock, suffering from fatigue, working 16 to 20 hours a day, they are getting very little time between shifts.
"That causes fatigue and burn out, coupled with the strains of dealing with public order, the ferocity of the attacks in the face of the most horrible provocation, all of that can lead to mental scars.
"The fact they are under-resourced and having to work all those hours is adding to that."
A spokesman for the PSNI said there had been no increase in the number of psychiatric referrals over recent months.
The Police Federation met Northern Ireland Attorney General John Larkin QC to discuss its concerns.
It is pressing for 1,000 extra officers to be recruited.
The strength of the force stands at around 7,000 officers after it was cut from its pre-ceasefire level.
Officers still face a severe threat from dissident republicans and there has been serious sectarian rioting involving loyalists.
Following a troubled marching season last year, Belfast City Council - on December 3 - decided to restrict the flying of the Union Flag from Belfast City Hall to designated days, a move which prompted months of loyalist rioting and spilled over into violence surrounding parades this summer.
Mr Spence said since 3 December last year, 451 officers had been hurt.
While many were not seriously hurt, others remained off work with broken bones, as a result of being hit with bricks or large stones.
Officers have sustained broken legs, arms and elbows.
Some have been knocked unconscious, others have lost teeth.
Earlier this month, the Police Federation - which represents rank and file officers - called for all contentious parades in Northern Ireland to be stopped for six months.
The Federation chairman said: "The Police Service of Northern Ireland (PSNI) are holding the fabric of Northern Ireland together, our politicians have failed us and members of the PSNI are trying to keep things together under hugely difficult circumstances.
"That is a fact of life and while there is no political consensus on how to deal with parades we are going to continue to see this."
US diplomat Dr Richard Hass is to chair multi-party political talks aimed at resolving contentious issues this autumn.
Mr Spence added: "The Secretary of State (Theresa Villiers) needs to ensure we have the resources we need to meet the terrorist threat and public disorder that we face on a nightly basis."
A PSNI spokesman said a 24/7 confidential telephone line was available along with employee support officers and a range of other psychological and psychiatric assistance.
"Police are not in a position to comment on numbers of officers seeking support, psychiatric or otherwise, however we can state that there has been no increase in the number of psychiatric referrals over recent months," he said.
"As an organisation, the PSNI offers an award-winning occupational health and wellbeing (OHW) service and the department was the first of it's kind in UK policing.
"OHW is staffed by highly-experienced and fully-trained medical and professional staff who offer a wide range of services including assessment, treatment and rehabilitation."
Prior to this marching season, a series of wellbeing seminars were held for frontline officers.