The number of people driven out of their homes by paramilitary and sectarian intimidation in Northern Ireland is at a five-year high, according to figures obtained by the Guardian.

Campaigners accuse the police of covering up the role of loyalist terror groups that are supposed to be on ceasefire.

In 2012/13 there were 411 cases of individuals and families informing the Northern Ireland Housing Executive that they were homeless because they had been driven from their properties, according to figures from the public housing authority.

That was a 36% increase on 2011/12 when there were 303 cases of victims seeking to be rehoused. In 2008/9 there were 288 cases.

Raymond McCord, whose son was murdered by an Ulster Volunteer Force (UVF) unit in north Belfast in 1997, and who campaigns against continuing paramilitarism, said the true figures for those made homeless through terror and intimidation may be three times as high.

He claimed that in many cases the Police Service of Northern Ireland (PSNI) was reluctant to sign forms apportioning blame to paramilitary movements that are officially on ceasefire.

McCord said this was a problem especially for those who owned their homes and who were not included in the Housing Executive statistics.

Under the Special Purchase of Evacuated Dwellings (Sped) scheme, the authorities can buy back houses from people who have been intimidated into leaving their homes. But in cases where the householders or families allege that paramilitary groups were involved, a senior police commander has to sign a form stating which organisation was responsible for the intimidation.

McCord cited the case of a relative of Bobby Moffett, who was murdered by the UVF in 2010. "I dealt with the case of this lad who was beaten very badly outside a bar earlier this year by members of the UVF on the Shankill Road," he said. "They picked on him because he won't be silenced after what happened to Bobby Moffett. After his beating he was informed he had to leave the Shankill and sought to be rehoused elsewhere in Belfast.

"The PSNI refused to sign the Sped form that would have said the UVF was behind this assault. This is because the chief constable, Matt Baggott, has said recently that the UVF ceasefire has not been broken. Instead the police refer to 'criminal elements' being responsible for assaults like this. It does not look good politically either for the PSNI or the Northern Ireland Office if an official government Sped form states a certain paramilitary organisation was behind the attack or ones like it."

McCord's battle to expose links between Royal Ulster Constabulary special branch and elements of the North Belfast UVF in the murder of his son and up to a dozen other deaths led to a damning report by the former police ombudsman Nuala O'Loan which found collusion between loyalist informers and their police handlers.

McCord said the PSNI's refusal to confirm via the Sped forms that paramilitaries were openly involved in intimidation and exiling denied victims a chance to offload properties they could no longer live in.

He said his latest case involved a businessman in the Greater Shankill area who faced demands from the local UDA for £100,000 in protection money. "This man may have to move home and resettle elsewhere, so are the PSNI going to refuse to officially acknowledge exactly who is behind this attempted extortion?"

One of the worst cases since 2012 has been that of Jemma McGrath, a 24-year-old care worker who was shot in the stomach outside a house in east Belfast in September this year. She had earlier been forced out of east Belfast by a local UVF commander who has been behind a wave of criminality and sectarian violence connected with the flags dispute over the last 12 months.

McGrath is a former partner of the UVF east Belfast "brigadier". After she fell out with him she was subjected to a campaign of malicious gossip, forcing her to flee to the north of the city. When she returned to the east on 25 September, UVF gunmen were waiting and shot her four times.

McCord said of the Housing Executive figures: "In Greater Belfast alone, judging the amount of cases, I would say it is double that figure. Across Northern Ireland there are other incidents of intimidation and exiling going on. So the figure is far, far higher than the Housing Executive's numbers."

Republican dissidents have been responsible for a spate of forced expulsions, particularly in Derry, in the same period.

The PSNI said it took the issue of intimidation "very seriously". Responding to McCord's allegations about senior police refusing to confirm paramilitary groups' involvement on Sped forms, a spokesperson said: "The PSNI is required to confirm that there is evidence to satisfy the second eligibility criteria, namely 'that it is unsafe for the applicant or a member of the household residing with him/her to continue to live in the house, because that person has been directly or specifically threatened or intimidated and as a result is at risk of serious injury or death'.

"The criteria has been set at a high level and in reaching a determination PSNI takes care to consider all relevant information and applies the criteria fairly and consistently. The assistant chief constable for operational support makes a security assessment based on confidential information held by local police regarding reports made by individual applicants. The individual is responsible for reporting any incidents to the police as they occur."

The spokesperson said they could not discuss any individual's security, but "if we receive information that a person's life may be at risk we will inform them accordingly. We never ignore anything which may put an individual at risk."