The widow of murdered Belfast solicitor Pat Finucane has said it is time for the truth to come out about his killing after “35 years of cover-ups”.

Geraldine Finucane was speaking after the Government ordered a public inquiry into the collusion-linked loyalist paramilitary murder of the lawyer in 1989.

Mr Finucane, 39, was shot dead at his family home in north Belfast by the Ulster Defence Association in an attack found by a series of probes to have involved collusion with the state.

I look forward to having the opportunity to participate in a statutory inquiry and expose publicly the whole truth behind the murder of my husband

His widow and the couple’s three children have been campaigning for decades for a public inquiry to establish the extent of security force involvement.

Northern Ireland Secretary Hilary Benn made the announcement to the House of Commons.

Speaking later in Belfast, Mrs Finucane said it had been a “long journey” to this point.

She said: “I look forward to having the opportunity to participate in a statutory inquiry and expose publicly the whole truth behind the murder of my husband.

“This has always been the objective of the campaign that my family and I have pursued for the last 35 years.

“We have only ever been concerned with uncovering the truth.

“It is this that has kept us going. It is the thing that has been missing, all these years.”

Mrs Finucane became emotional as she delivered her statement.

She said she did not believe the murder of her husband was “simply the work of gunmen who killed him”.

She added: “An independent, statutory public inquiry is and was the only way to bring the whole truth behind the murder of Pat Finucane into the light of day.”

Mrs Finucane said she believed the public inquiry could be a “watershed moment” in dealing with legacy cases in Northern Ireland.

She added: “If a public inquiry in to the murder of Pat Finucane can finally publicly examine all of the collusion that plagued our society for so many years, then there is hope that the real process of healing can begin.

After 35 years of cover-ups, it is time for truth

“The murder of Pat Finucane is the last remaining Weston Park case.

“It is high time it was properly investigated, publicly examined, and finally resolved.

“I believe that my family deserve this after so many years. Pat Finucane deserves this after so many years.

“Society as a whole deserves this, after so many years. After 35 years of cover-ups, it is time for truth.”

Mrs Finucane received a round of applause from supports as she finished speaking.

Earlier, Mr Benn told the Commons it is a “plain fact” that a UK government commitment made more than 20 years ago to hold an inquiry into Mr Finucane’s murder “remains unfulfilled”.

“It is for this exceptional reason that I have decided to establish an independent inquiry into the death of Patrick Finucane under the 2005 Inquiries Act,” he said.

The court acknowledged Mrs Finucane had been given an “unequivocal undertaking” by the government following the 2001 Weston Park Agreement that there would be a public inquiry into the murder.

However, the Supreme Court judges found that the government had been justified in later deciding against holding one.

The court said it was up to the government to decide what form of investigation was now required.

The following year, the government pushed back a decision on a public inquiry, insisting outstanding issues concerning the original police investigation needed to be first examined by the Police Ombudsman for Northern Ireland.

In the years since, Mrs Finucane has pursued further legal proceedings challenging the ongoing delays on a decision.

During the summer, the Court of Appeal in Belfast gave the Government a September deadline to confirm what form of human rights-compliant investigation it intends to undertake into the murder.

The Secretary of State said he had considered the “likely costs and impact on the public finances”.

“It is the Government’s expectation that the inquiry will – while doing everything that is required to discharge the state’s human rights obligations – avoid unnecessary costs given all the previous reviews and investigations, and the large amount of information and material that is already in the public domain,” he said.

Mr Benn said he also considered referring the case to a new mechanism established to examine Troubles killing in Northern Ireland – the Independent Commission for Reconciliation and Information Recovery.

“However, given the unique circumstances of this case, and the solemn commitment made by the government in 2001 and again in 2004, the only appropriate way forward is to establish a public inquiry,” he said.

“Many of us in this House remember the savage brutality of the Troubles – a truly terrible time in our history – and we must never forget that most of the deaths and injuries were the responsibility of paramilitaries, including the Ulster Defence Association, the Provisional IRA, and others, and we should also always pay tribute to the work during that time of the Armed Forces, the police and the security services, the vast majority of whom served with distinction and honour, and so many of whom sacrificed their lives in protecting others.

What we can do is to seek transparency to help provide answers to families, and to work together for a better future for Northern Ireland

“It is very hard for any of us to understand fully the trauma of those who lost loved ones – sons and daughters, spouses and partners, fathers and mothers – and what they have been through, and there is of course nothing that any of us can do to bring them back or to erase the deep pain that was caused.

“But what we can do is to seek transparency to help provide answers to families, and to work together for a better future for Northern Ireland which has made so much progress since these terrible events. I hope that this inquiry will, finally, provide the information that the Finucane family has sought for so long.”

Mr Benn said the Government would seek to appoint an inquiry chair and establish its terms of reference “as soon as possible”.

It is our hope that the inquiry and its findings will provide the information the Finucane family have been looking for

A spokesperson for the US Department of State welcomed the commitment to set up a public inquiry.

The spokesperson said: “We recognise the complexity in addressing the legacy of violence in Northern Ireland as well as the deep and enduring pain of those who lost loved ones.

“It is our hope that the inquiry and its findings will provide the information the Finucane family have been looking for.”