It has been reported in Spain that senior Sinn Fein politicians were involved in the negotiations which led to the Eta ceasefire.
Eta announced a ceasefire on Wednesday
The ceasefire by the Basque terrorist group came into effect at midnight.
One newspaper, El Mundo, says that former Belfast Lord Mayor Alex Maskey was an architect of the process.
North Belfast assembly member Gerry Kelly is also said to have been involved. Belfast priest Father Alex Reid has confirmed he played a role.
Mr Maskey said the lessons learned in Northern Ireland had been invaluable to those negotiating a peace deal in Spain.
He said senior members of Sinn Fein had visited the Basque region of northern Spain and people from that area had come to Northern Ireland.
Mr Maskey said they examined "in some considerable detail the pros and cons of our peace process, the often convoluted twists and turns" of the process in Northern Ireland."
He added that they were "learning the lessons essentially of how we have managed to move from a situation of conflict through negotiations into trying to find a way forward through peaceful dialogue".
Eta has been blamed for killing more than 800 people in its four-decade campaign for independence for the Basque region of Spain and south-west France.
In a statement released to Basque media on Wednesday, the group said its objective now was "to promote a democratic process in the Basque country".
It urged both Spain and France to enter into peace negotiations.
The European Union on Thursday welcomed the ceasefire, saying it was a "very positive sign".