John McDonnell (pictured at the High Court earlier this month) admitted today he 'longs for a united Ireland' as Theresa May heads to Brussels to fight for the Union in Brexit talks

John McDonnell admitted today he 'longs for a united Ireland' as Theresa May heads to Brussels to fight for the Union in Brexit talks.

The shadow Chancellor declared himself an unrepentant Irish Republican during a Westminster lunch.

Mr McDonnell - who been criticised for suggesting in the past IRA terrorists should be 'honoured' - insisted he 'recognised democracy' was the only route to uniting Northern Ireland and the Republic.

He said 'contortions' in the Brexit deal was not the way to remove Northern Ireland from the United Kingdom.

The Good Friday Agreement provides for uniting if both Northern Ireland and the Republic separately vote in favour in a referendum.

The remarks are likely to be seized upon by Theresa May as she negotiates with the Unionist DUP over Brexit.

DUP leader Arlene Foster props up Mrs May in the Commons and has threatened to veto any Brexit deal which does not meet her red lines - but will be warned blocking a deal could open the door to an election which could let Labour into Downing Street.

Mr McDonnell said: 'I'm a Republican - I long for a united Ireland but I recognise democracy.

'Ireland will not be reunited on the basis of some contortion in the relationship with the EU.

'It will only be reunited on the basis of the popular support of the Irish people. That's what I respect.

'One of the concerns we have got through all this on all sides of the Republican debate is nothing in these discussions should cause any damage to the Good Friday Agreement which I think was a huge achievement.'

Mr McDonnell's remarks will likely be used to warn DUP leader Arlene Foster (pictured in Dublin on Monday) of the dangers of letting Labour into Downing Street if Theresa May cannot get a Brexit deal

Mrs Foster admitted last year that a Labour government led by Jeremy Corbyn and Mr McDonnell would be 'disastrous' for Northern Ireland.

The former first minister - who is currently not filling the role because of a near two-year breakdown in powersharing - told the House Magazine: 'Despite the fact that we have a confidence-and-supply arrangement with the Conservative party, they have, in terms of the Northern Ireland office, gone out of their way to be neutral in their dealings here in Northern Ireland.

'You would not have that with a Jeremy Corbyn Northern Ireland office. He would be very clearly partisan towards republicanism.

'It would be disastrous for Northern Ireland because of his previous utterances in relation to Northern Ireland and his support for the IRA at a time when nobody else was supporting the IRA.'