Mr Shekari was kidnapped on Sunday and released at about 10:30 p.m. on Monday, according to the chancellor of the Catholic Diocese of Kafanchan.
Mr Kukah had yet to honour the invitation as of Saturday afternoon, The Gazette understands.
The clergyman also abused an 11-year-old girl in Wuppertal in 2011 when she visited him with a friend.
The report shows about 216,000 minors – boys between ages 10 and 13 – have been sexually abused since 1950.
The two priests were attacked at the St Vincent Ferrer Catholic Church, Malumfashi in Katsina state by unknown gunmen on Thursday night.
