Sinn Fein lawmaker Martin McGuinness on Thursday said he was "not in any physical state" to stand in the vote, scheduled for March 2.

The 66-year-old resigned as deputy first minister last week after a row with his party's power-sharing partners,triggering a snap election.

In an interview with the Press Association news agency, McGuinness said he was confronting a "very serious illness which has taken a toll."

"I am very determined to overcome this condition but it is going to take time," he added.

Key figure in politics

McGuinness, who served as deputy first minister for more than 10 years, played a prominent role in both the start and the end of Northern Ireland's three-decade conflict in which more than 3,600 people died. He was a former commander in the Irish Republican Army paramilitary group that fought for the province to leave Britain and join the Republic of Ireland. Together with Sinn Fein president Gerry Adams he later helped forge the 1998 peace agreement that largely brought an end to the fighting.

McGuinness resigned from his post earlier this month over First Minister Arlene Foster's handling of a controversial green-energy subsidy scheme, leading to the collapse of the power-sharing government.

In a statement, he said the political crisis combined with his health problems had forced him to bring forward his plan to step aside.

"It was my intention to step aside in May this year," McGuinness said. "Unfortunately, my health and the current crisis have overtaken this timeframe. I am not physically able to continue in my current role and have therefore decided to make way for a new leader."

'Champion of the peace process'

Following Thursday's announcement, British Prime Minister Theresa May sent McGuinness her "best wishes for his retirement."

"He played a key role in moving the Republican movement towards a position of using peaceful and democratic means," she said.

Gerry Adams also paid tribute to his colleague. "I want to express my heartfelt thanks to Martin. He and I first met over 45 years ago behind the barricades in Free Derry and have been friends and comrades since."

Irish Prime Minister Enda Kenny described him as "a tireless and committed champion of the peace process."

"While Martin and I may not always have seen eye-to-eye on every issue, I readily acknowledge the remarkable political journey that he has undertaken."  

McGuinness said Sinn Fein would announce his successor next week.

nm/kl (Reuters, AFP)