Twin sons of Iraqi Ambassador to Portugal Saad Mohammed Ridha have been under investigation after they beat a Portuguese boy into coma for several days, local media reported on Tuesday.

In an exclusive interview with Portuguese TV broadcaster SIC aired on Tuesday, the sons of the Iraqi ambassador Haider and Ali Ridha, 17, said that they collaborated with Portuguese police without invoking diplomatic immunity, and they will not leave Portugal until the case is closed.

"We respect all the police proceedings and even though we did not do it, we could have invoked diplomatic immunity and we would not have had to answer any questions or investigation,"one of the ambassador's sons told SIC.

On Wednesday, Ruben Cavaco, 15, was assaulted by Haider and Ali Ridha in Ponte de Sor, some 180 km northeast of Lisbon, and suffered multiple fractures. He was transferred to the Hospital of Santa Maria in Lisbon and left the intensive care on Tuesday morning after several days in coma.

In a statement released on Monday, the Iraqi embassy in Lisbon said that the ambassador's sons were acting in legitimate self-defense after being "severely beaten" and insulted by six people.

Portuguese Foreign Minister Augusto Santos Silva said that the case is extremely serious and the diplomatic immunity for the two sons of Iraqi ambassador could be lifted if it is necessary for justice to be done, with the cooperation of the Iraqi authorities.

The Iraqi ambassador has been summoned and returned to Baghdad on Tuesday over the case.