He also said it was “absolutely clear” the British and Irish governments must remain neutral in any border poll. “That is their obligation and their responsibility,” he said.
Mr Corbyn made his comments as he delivered the annual Bloody Sunday lecture in the Guildhall in Derry in Saturday afternoon.
It is one of a number of events taking place in the city this weekend to mark the 50th anniversary of the atrocity on Sunday.
On January 30th, 1972, members of the British army’s Parachute Regiment opened fire on anti-internment marchers in the city’s Bogside, killing 13 and mortally wounding another, and injuring others.
Mr Corbyn, who is now the Independent MP for Islington North, said the vagueness of the Belfast Agreement – which states that the Northern Secretary shall call a poll if it appears likely that a majority would vote for a united Ireland – meant clarity was needed.
“The British government especially has an obligation to explain how the poll will be triggered, and I call them on to begin that process so we can have that understanding and that discussion,” he said.
The former Labour Party leader also condemned the UK government’s proposals to introduce a statute of limitations which would ban future prosecutions for Troubles-era crimes, as well as civil cases and inquests.
Mr Corbyn said it was an “outrage” that nobody has been prosecuted for the deaths on Bloody Sunday and it was a “double outrage that the British government is now planning legislation to make it harder for such an effort to succeed at any time in the future.”
The “forthcoming amnesty Bill”, he said, “would shut down all further inquiries into the state’s actions during the Troubles. Such a law … would have prohibited the Saville Inquiry into Bloody Sunday,” he said.
“Introducing a statute of limitations for atrocities that took place in Ireland amounts to nothing short of complicity in covering up the truth and ensures that the lessons are not fully learnt.”
The Bill, he said, would “entrench injustice and actually be an insult to us all,” he said.
Mr Corbyn paid tribute to the Bloody Sunday relatives and other campaigners and said that they and the city of Derry were an inspiration to all those who fought for justice.
He backed the call made by the Foyle MP, the SDLP leader Colum Eastwood in the House of Commons earlier in the week for an apology from the Parachute Regiment, but said that more was needed and called on the UK gov