Londonderry's newly-elected mayor is facing criticism over his support for the Bloody Sunday families.
Colum Eastwood, SDLP, accepted the chain of office on Monday night.
He said the publication of the Saville Report into Bloody Sunday next week, would be "difficult and emotional".
He offered the families his support on behalf of the people of Derry. But Gregory Campbell, DUP, warned him it was "deeply controversial" and he could not claim to speak for everyone.
Mr Eastwood said his policy as mayor would be to have an "open door".
"I intend to go to whatever community invites me. I want to be a mayor for everybody - not just the people from my background," he said.
But Mr Campbell argued: "No-one can say whatever they want to say about the Saville Report and purport to represent the views of the entirety of the city. It just won't be possible."
Thirteen people died after paratroopers opened fire during a civil rights march in Londonderry on 30 January 1972. Another person died of his injuries some time later.
The report of the Bloody Sunday Inquiry is due to be published on 15 June.
Families of those who died or were injured, and the soldiers most directly involved, will be able to see it some hours before it is made public.
There will also be a debate in the Commons on the report in the autumn.
The inquiry by Lord Saville opened at the Guildhall in 1998 and heard evidence from more than 900 people.
The inquiry finished hearing evidence in 2004, with the report initially due for publication the following year.