The family of Israeli prime minister Naftali Bennett has received a death threat and bullet in the post for the second time this week, police said.

Israeli media say the target of the threats was Mr Bennett’s 17-year-old son.

In a nationwide speech marking Israel’s Holocaust memorial day, Mr Bennett lamented the deep polarisation in Israeli society as he warned his citizens against letting internal divisions tear society apart.

“My brothers and sisters, we cannot, we simply cannot allow the same dangerous gene of factionalism dismantle Israel from within,” Mr Bennett said in Wednesday night’s ceremony, broadcast on national TV.

Mr Bennett’s speech, coming on one of Israel’s most solemn days of the year, came in a deeply personal context.

Just a day earlier, his family received a letter with a live bullet and a death threat.

Israeli authorities tightened security around the premier and his family and were investigating.

That prompted his son oldest son Yoni to write on Instagram how upsetting the episode had been.

“It’s just sad to see that real people write such horrible things,” he said.

“To think that he lives and breathes like me but has a brain that was created by the devil is crazy.”

Israeli media said Yoni, who is 17, was the target of Thursday’s threats.

Mr Bennett leads a narrow coalition that recently lost its parliamentary majority.

His government is made up of eight parties that have little in common beyond their shared animosity to former prime minister Benjamin Netanyahu, and Mr Netanyahu, now the opposition leader, has worked hard to deepen divisions within the coalition.

Mr Bennett’s government was formed after four inconclusive elections, underscoring the fissures in society over key issues, including the conflict with the Palestinians and relations between religious and secular Jews.