* 18-year-old Israeli arrested for hoax bomb threats
* He is alleged to have targeted Jewish centres
* Defence says a "benign growth" is behind his behaviour (Adds defence lawyer's comments, police amend suspect's age)
By Jeffrey Heller
JERUSALEM, March 23 (Reuters) - A young Israeli man who also holds U.S. citizenship was arrested in Israel on Thursday on suspicion of making dozens of hoax bomb threats against Jewish community centres in the United States and several other countries.
At a court hearing near Tel Aviv, the suspect's defence attorney said the young man has a growth in his head that causes behavioural problems.
A police spokesman said the suspect, whose identity could not be reported under a court order, is 18, Jewish and a dual U.S.-Israeli national. Police initially gave the suspect's age as 19.
U.S. federal authorities have been investigating a surge of threats against Jewish organisations, including more than 100 bomb threats in separate waves over the past three months against Jewish community centres (JCCs) in dozens of states.
The incidents have stoked fears in the U.S. of a resurgence in anti-Semitism and forced the evacuation of many centres, including some with day care for young children.
Israeli police said FBI agents participated in the probe in Israel that led to Thursday's arrest.
The suspect covered his face with his sweatshirt as he entered the court. The court extended his police detention for eight days.
"We believe he is responsible for the wave of calls, bomb threats, made to Jewish community centres in the United States," the police spokesman said.
He added that the suspect, who is alleged to have also targeted centres in Australia and New Zealand, began making the calls three months ago using advanced masking technologies.
The spokesman said the suspect's home was searched on Thursday.
Galit Bash, the suspect's defence attorney, said a medical condition was the root of problem. "My client ... suffers from a very serious medical problem, a problem that may affect his behaviour, his ability to understand right and wrong," his defence attorney told Reuters.
Israel's Channel 10 news quoted her as telling the court he had a benign growth in his head.
She said her client was home-schooled and incapable of holding down a job. She added he had been found medically unfit for Israel's compulsory military service.
Police said the suspect was responsible for a bomb threat against Delta Airlines flight 468 in January 2015 at New York's John F. Kennedy airport. (Additonal reporting by Maayan Lubell and Baz Ratner and Rami Amichay in Rishon Lezion; Editing by Vin Shahrestani)