DUP deputy leader Nigel Dodds says even though he knew Martin McGuinness was very ill, his death had come as a "terrible shock".

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Mr Dodds it was a difficult day for victims of violence but sent his condolences to the McGuinness family. He said that while we "cannot whitewash history, we pay tribute to Martin McGuinness, to Ian Paisley, to all of those who brought us to a better place we're in today".

The chair of the Community Relations Council, Peter Osborne, said Martin McGuinness made a huge contribution to the peace process in Northern Ireland. 

In a statement, external , Mr Osborne said: "He did much to promote reconciliation with significant civic leadership and many acts that went beyond the symbolic to lead by example. When enemies reconcile it says much for all involved."

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Former prime minister Tony Blair says Martin McGuinness was always very clear why peace at that time was consistent with the principles of republicanism. 

Mr Blair said what made McGuinness such a "formidable foe" during the arms struggle made him such a "formidable peacemaker" later.  

Watch former Northern Ireland secretary Peter Hain's reaction to the death of Martin McGuinness . 

Former Conservative cabinet minister Lord Tebbit was one of those injured by an IRA bomb in Brighton's Grand Hotel in 1984. His wife was left paralysed in the attack.

"He was a coward, " Lord Tebbit told Good Morning Britain. 

"The reason he suddenly became a man of peace, was that he was desperately afraid that he was going to be arrested and charged with a number of murders."

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"It's not merely that these creatures crippled my wife, but they also murdered five of my close friends. I only hope that his death will help to bring some sort of closure to those families and friends of those whose murders he accomplished."

Here's a lookback at the political career of former Northern Ireland deputy first minister Martin McGuinness. 

Michelle O'Neill, who became Sinn Féin's northern leader after Martin McGuinness quit politics in January, says he promoted "peace and reconciliation and a genuine commitment to equality and respect". 

Image source, Pacemaker

"Growing up as a young republican, I was inspired by Martin McGuinness and I continue to be today.

"His leadership, grace and warm personality have transformed Irish politics for the better and his impact will be felt for many years to come." 

The son of Jean McConville, one of the Disappeared , gave his reaction to the death of Martin McGuinness earlier - listen back to Michael McConville on BBC Radio 4's Today Show below. 

Democratic Unionist Leader Arlene Foster has commented further on Martin McGuinness - she says that while "history will record differing views and opinions" on him, McGuinness' contribution to the peace process was "significant". 

Image source, Pacemaker

"He served the people of Northern Ireland as deputy first minister for nearly a decade and was pivotal in bringing the republican movement towards a position of using peaceful and democratic means."

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Tony Blair, prime minister at the time of the Good Friday agreement, said that "whatever the past of Martin McGuinness, I don't think it's inappropriate, today, to remember what he did for peace" for the island of Ireland, and for showing leadership in resolving "one of the great conflicts in the world".

Mr Blair said Mr McGuinness had brought his steel and ruthlessness to the peace process. 

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Once he had come to see that the armed struggle was causing misery and peace was the right way forward, he pursued it with skill and courage, he told the Today programme.

Mr Blair said when sitting around the table with Mr McGuinness he never put out of his mind the victims of terrorism, but believed that in getting an agreement there was "the possibility to avoid more bloodshed in the future".

"Without the involvement of Martin, we would never have had that accord," he added.

Taoiseach (Irish Prime Minister) Enda Kenny says Martin McGuinness was one of the "chief architects of the Good Friday Agreement" and his death is a "significant loss, not only to politics in Northern Ireland but to the wider political landscape".

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In a statement, external , Mr Kenny said: "Martin will always be remembered for the remarkable political journey that he undertook in his lifetime.  Not only did Martin come to believe that peace must prevail, he committed himself to working tirelessly to that end."

Sinn Féin members of the Northern Ireland Assembly have been tweeting their tributes and photos of Martin McGuinness