Peter Robinson and Martin McGuinness did not meet Pope
The first and deputy first ministers were invited to a ceremony to mark the arrival of the Pope in Edinburgh this morning, but did not not attend.
Peter Robinson and Martin McGuinness were asked to be among the dignitaries presented to the Pope by the Queen.
Mr Robinson said he did not go because he had to attend the opening of the New York stock exchange's new premises in Belfast on Thursday afternoon.
Mr McGuinness also attended the opening and described it as "very important".
The deputy first minister said the Pope was on a state visit to Britain.
He added that he would be very pleased to greet the pontiff in Ireland.
Mr Robinson described the stock exchange event as having huge significance and said that it was very important for Northern Ireland.
However, the SDLP accused both men of "hiding behind a flimsy excuse of being busy".
SDLP MLA Delores Kelly, who is a member of the Stormont committee which scrutinises the work of the Office of the First and Deputy First Minister, criticised Mr Robinson and McGuinness on their absence from the ceremony.
She questioned why they could not find the time when other ministers were able to attend.
She said it was a missed opportunity for Mr Robinson and Mr McGuinness to show they had moved on.
Pope Benedict XVI shook hands with the first ministers of Scotland and Wales during the royal reception at Holyrood House in Edinburgh on Thursday morning.
The Queen and the pontiff praised each other's institutions on their role in helping the Northern Ireland peace process.
Buckingham Palace officials had issued briefing notes which said Mr Robinson would be there.