First Minister Peter Robinson said he was glad the deputy first minister had accepted the invitation.
We recognise that this will be a difficult ask for Her Majesty the Queen and a significant step for republicans.
The process has required us all to reach out and take decisions outside our comfort zone.
It is the right decision and a step forward for Northern Ireland.
More top news
Police in Bangladesh have begun a raid on a restaurant where gunmen are holding 20 people hostage.
Right-wing think tank warns leaving the UK in order to remain in the EU would turn Scotland into 'Greece without the sun'.
A poll of Britain's largest trade union, seen by ITV News, indicates more than half of those surveyed think the Labour leader should quit.