U.S. Attorney Preet Bharara is looking into Mayor de Blasio’s involvement in the sale of Long Island College Hospital in Brooklyn, the Daily News has learned.

Bharara’s office recently issued a subpoena to the State University of New York, which had owned the hospital, seeking all communications between the university system and City Hall regarding the sale of LICH dating to Jan. 2, 2014, when de Blasio took office, said two sources familiar with the matter.

One source close to SUNY confirmed the subpoena and said “the clear target seems to be de Blasio.” But the specifics of what Bharara is looking into were unclear.