JERUSALEM (REUTERS) - Israel's ruling coalition became a minority in Parliament on Thursday (May 19) when an Arab lawmaker from a left-wing party quit, leaving Prime Minister Naftali Bennett with a more precarious grip on power.

The defection by Ghaida Rinawie Zoabi leaves Bennett controlling 59 of the 120 seats in the Knesset. In a letter to the prime minister, she cited ideological differences.

The opposition could seek to exploit her walkout by submitting a motion on Wednesday to dissolve the government and hold an early election. In a possible reprieve for Bennett, Zoabi stopped short of saying she would vote in favour.

In her letter Zoabi, a legislator from the Meretz party, referenced an escalation in violence at a Jerusalem holy site as well as tactics by Israeli police at the funeral last week of a Palestinian journalist.

"I cannot keep supporting the existence of a coalition that shamefully harasses the society I came from," she said in the letter circulated in Israeli media.

She acknowledged that voting to dissolve the government may not be in the interest of the Arab public who make up about 21 per cent of the Israeli population.

"I'm not under any illusions. I know that this coalition may be the sanest possible option - including for the Arab public," she told Channel 12 TV. "I'm not going to blow it up automatically."

Bennett heads a collection of left-wing, centrist, right-wing and Arab parties that was sworn in a year ago, ending Benjamin Netanyahu's record 12-year run as prime minister.

It lost its slight majority last month when a lawmaker from Bennett's own right-wing party quit the coalition.

The government is now more vulnerable and may seek external support to buttress itself against no-confidence votes in parliament.