Former Irish prime minister Garret FitzGerald has died in hospital in Dublin after a short illness.

Mr FitzGerald, who was 85, served twice as taoiseach between 1981 and 1987 at the head of two coalition governments.

He was Fine Gael taoiseach at the time of the signing of the Anglo-Irish Agreement in 1985.

Tributes have poured in for Mr FitzGerald, with the Queen describing him as a "true statesman" who would be greatly missed.

Mr FitzGerald retired from the Dail in 1992, but still took part in political campaigns, particularly on the Nice and Lisbon Treaties.

Mr FitzGerald, a former economics lecturer, was elected to the Seanad (the Irish Senate) in 1965 and the Dail in 1969.

When Fine Gael entered government in 1973 he was appointed foreign affairs minister.

He also played a leading role in the Sunningdale Agreement negotiations which led to the short-lived power-sharing executive in Northern Ireland.

Analysis In the words of one Irish government official Garret FitzGerald was the grandfather of the nation. He enjoyed widespread respect and admiration even among his political opponents. He is credited with stimulating the peace process in Northern Ireland by negotiating the Anglo-Irish Agreement in 1985 with the then Prime Minister Margaret Thatcher. Politicians in Dublin say this week's visit to Ireland by the Queen would not have been possible without the work started three decades ago by Dr FitzGerald.

The Queen said in a statement on Thursday that she was saddened to hear of Mr FitzGerald's death.

"A true statesman, he made a lasting contribution to peace and will be greatly missed," the statement said.

"Please will you convey my sincere condolences to his family."

Irish President Mary McAleese said Mr FitzGerald had been steeped in the history of the state and was someone who "constantly strove to make Ireland a better place".

"His thoughtful writing, distinctive voice and probing intellect all combined to make him one of our national treasures," she said.

"Above all, Garret FitzGerald was a true public servant."

The Irish prime minister and Fine Gael leader Enda Kenny said Mr FitzGerald was "a truly remarkable man who made a truly remarkable contribution to Ireland".

He described him as the "epitome of high honour and decency in public life" and said his "towering intellect, enthusiasm for life and optimism" would be "missed by everyone".

Prime Minister David Cameron said Mr FitzGerald had made a "huge contribution to the peace process".

Image caption Garret FitzGerald with Margaret Thatcher after the signing of the Anglo Irish Agreement

Northern Ireland Deputy First Minister Martin McGuinness said the former premier had been "a major figure in Irish politics over many decades".

'Courageous'

He said he had only got to know him in later life as Mr FitzGerald was "not interested" in meeting with Sinn Fein representatives during his time as taoiseach and leader of Fine Gael.

"My dealings with him only came in the aftermath of the Good Friday Agreement and the regular visits he made to the Patrick Magill Summer School (held in Glenties, County Donegal) and I think he and I got on very well," Mr McGuinness added.

"I think at the end of day he was someone very conscious there were very many different views and that's why he came to Glenties and that's why he was prepared to listen very carefully to views, many of which would be the opposite of what he believed."

Irish cabinet minister Joan Burton said Mr FitzGerald was an "extraordinary figure in Irish politics".

"In terms of his personal history, his mother was from Presbyterian stock from the north and his father was a very distinguished republican and statesman," she said.

"Dr FitzGerald was one of the initiators of the peace process both in his time as minister for foreign affairs and in the administration that he led in the 1980s.

"He was a great man and he had really endearing personal characteristics, he was extremely approachable.

Image caption The Irish flag flies at half mast over Government Buildings in Dublin

"He was very courageous, when Ireland was emerging from a dominant clericalism he was one of the voices who actually broke out to create a more secular state in which religion is honoured but the business of the state is the business of the Republic and not completely entwined with that of particular churches."

'Reformer'

Former SDLP leader John Hume said Mr FitzGerald had been a "moderniser and reformer" who helped "change the face of Irish politics for the better".

He said:"The SDLP worked closely with Garret over many decades and supported him as he displayed great intellectual foresight and inner fortitude to develop initiatives such as the New Ireland Forum and the Anglo-Irish Agreement which allowed us to open new chapters in our history and ultimately paved the way to peace and the democratic institutions we enjoy today."

Seamus Mallon, former SDLP deputy first minister, said he was "saddened on a personal and political level".

Mr Mallon said he admired the approach Mr FitzGerald had brought to his role as taoiseach and the political process.

Mr Fitzgerald will be buried after a state funeral in Dublin on Sunday.