Former International Monetary Fund chief Rodrigo Rato says he plans to cooperate with justice officials after investigative tax agents searched his apartment and an office in Madrid.

Rato told leading the leading El Pais newspaper early Friday that he was "at home and free" after authorities took him from his home to be present during a search of one of his offices.

Rato, a former Spanish economy minister, was also present Thursday during the hours-long search of his apartment. Rato was then taken by police to his office and returned home after midnight.

The court handling the case said the investigation is secret.

He is also under investigation for his former role as chief executive of Spanish bank Bankia, which was bailed out in 2012.