Jerusalem ? A suspected Jewish extremist told investigators that his group had been planning simultaneous attacks on Muslim worshippers at mosques in Jerusalem, including Islam’s third holiest shrine, a security official said Tuesday.

The attacks were meant to avenge victims of Palestinian violence, said the official, who spoke on condition of anonymity.

In recent weeks, Israel’s Shin Bet security service has been investigating Jewish extremists in connection with shootings that killed eight Palestinian civilians.

Shahar Dvir-Zeliger, an alleged member of the group, told investigators the attacks were to take place during Friday prayers, when the Al Aqsa Mosque compound in Jerusalem and mosques across Israel would be crowded, the official said.

Muslims account for nearly 20 percent of Israel’s 6.6 million people.