Israeli Prime Minister Benjamin Netanyahu on Sunday offered to assist efforts by Nigeria's security forces to locate nearly 280 schoolgirls abducted a month ago by militant Islamist group Boko Haram.

"Israel expresses deep shock at the crime against the girls. We are ready to assist in finding the girls and combating the cruel terrorism inflicting your country," Netanyahu's bureau quoted him as telling Nigerian President Goodluck Jonathan.

Netanyahu phoned Jonathan from Japan where he arrived early on Sunday for a four-day state visit, the first by an Israeli premier in six years.

The statement released by Netanyahu's media adviser did not detail what form of assistance Israel was offering. The United States, Britain, France and China have reportedly been aiding the efforts to free the girls since last week.

Israel and Nigeria maintain close defense and intelligence ties, including arms sales to Abuja.