A rabbi known for his efforts to expose sexual abuse within New York's ultra-orthodox Satmar Hasidic community was attacked by a man who splashed what appeared to be bleach in his face.

Rabbi Nuchem Rosenberg, who maintains an online blog and an information hotline for abuse victims, was assaulted a day after a prominent member of the community was found guilty of repeatedly abusing a young girl who went to him for help.

The rabbi was a regular presence and staunch supporter of the victim at the trial of Nechemya Weberman, from the ultra-orthodox community in the Williamsburg quarter of Brooklyn. Weberman, an unlicensed therapist, was convicted by a jury at the New York State Supreme Court of abusing a girl who was sent to him for counselling. The abuse, which the girl said continued for three years, began when she was 12.

Weberman was convicted on Monday on 59 counts of abusing the girl. On Tuesday, Rabbi Rosenberg, who in the past has been ostracised for talking publicly about Satmar Jews whom he believed were sex abusers, was ambushed at around noon by an unidentified man as he walked down Roebling Street in Williamsburg.

"He comes up to me and he taps me on the shoulder," the 62-year-old activist told the New York Post after being treated in hospital for burns to his eyes. "He walked up hard to me. He looks me in the face. I saw him holding a glass. I thought it was coffee or something and he throws it in my face." He said he believed the attack was in retaliation for his support of Weberman's victim. Soon after the trial, the rabbi welcomed the verdict on Twitter, saying: "Burech hashem!! [Praise God!!]... Chazer [Pig] Weberman is arrested..."

No one has yet been arrested over the attack. Police told The New York Times that there had been an "ongoing dispute" between the rabbi and the man who attacked him this week. A police spokesman also told the paper that there appeared to be no connection between the attack and the conviction of Weberman.

The conclusion of the Weberman case on Monday was seen as a victory for prosecutors probing a community that has long faced accusations of intimidating victims.

Weberman, 54, was accused of exploiting his status to access victims who were seen as problematic for falling foul of the Satmar's strict norms on personal modesty. In the end, with no physical evidence to go on, the trial was a battle of testimonies, with the now 18-year-old victim's word pitted against Weberman. Sentencing is set for early next month, with Weberman facing the possibility of decades behind bars.

"The veil of secrecy has been lifted," the Brooklyn district attorney Charles Hynes said after the conviction, according to The New York Times.