An accused sex offender grabbed the rear end of City Council Member Sandy Nurse Tuesday morning during a surprise visit by elected officials to the jails, sources told the Daily News. Nurse whose district is in Brooklyn, Council Member Tiffany Caban of Queens and others were on the unannounced visit to the jails on Rikers Island in part to assess treatment of people held in special mental health units. As Nurse walked through an area at the George R. Vierno Center, detainee Gregorio Garcia grabbed her. Correction officers intervened and pulled Garcia away from Nurse, the sources said. Garcia entered the jails on Oct. 2 after being arrested in Manhattan on a sex abuse charge. Nurse, who has been a critic of conditions in the jails as chair of the council’s Criminal Justice Committee, declined comment late Tuesday. In a statement, DOC spokeswoman Annais Morales said, “The safety of all DOC employees, people in custody, and visitors is a top priority for the department. “This disturbing incident is under investigation. We are grateful to the members of service who quickly and professionally addressed the situation.” On Monday, Nurse, Caban, Council Member Mercedes Narcisse and Deputy council Speaker Diana Ayala called for a probe of extended lock-ins in mental health units on Rikers Island. The tour Tuesday was triggered by an article in The News in which a former jail social worker alleged severely mentally ill men were routinely locked in their cells for weeks and even months.