JERUSALEM -- Israel's prime minister faced a new scandal Tuesday after the attorney general ordered a criminal investigation into excessive spending at his residences.

While the investigation shows no sign of threatening Prime Minister Benjamin Netanyahu's hold on power, it nonetheless gave him a new headache at a time of growing international isolation and domestic turmoil with a narrow and fractured coalition.

Netanyahu and his wife, Sara, have for years faced scrutiny over their spending and have fended off accusations that their lifestyles are out of touch with regular Israelis. The prime minister has long been saddled with an image as a cigar-smoking, cognac-swilling socialite, while his wife has come under fire for her own expensive tastes and alleged abusive behaviour toward staff.

The attorney general's decision Monday came months after a report by the state comptroller, an official watchdog agency, that detailed large sums of public money spent on food, furniture, cleaning and gardening at the couple's official residence in Jerusalem and their private home in the exclusive coastal city of Caesarea. Cleaning expenses in that home alone averaged more than $2,100 a month in taxpayer's money, according to the report, even though the couple only spent the occasional weekend there.

The report also said the couple pocketed proceeds from recycling bottles that had been purchased for entertaining official guests. At the time, the report said that the bottle returns, and purchases of garden furniture for their private home, may have violated the law.

The Justice Ministry declined to comment on what or who exactly would be investigated, but Israeli media said those charges, as well as another involving unusually high payments for Netanyahu's longtime electrician, would be at the centre of the probe.

The Netanyahus are not expected to be questioned about the spending yet, with most of the focus directed at Ezra Saidoff, a staffer who oversees much of their affairs.

"It's another annoying headache," said Avraham Diskin, a political scientist at Jerusalem's Hebrew University. "But I don't think it is very significant unless it is proven that there were criminal offences and that somehow (Netanyahu) is connected to them." Diskin added that the chances for that were small.

Netanyahu has faced a bumpy few months since being re-elected for a fourth term in March. He forged a fragile, narrow coalition that is susceptible to the extortion of practically any lawmaker and is likely to struggle to make progress on much significant legislation.

Perhaps the biggest blow to Netanyahu was the signing last week of the international deal meant to curb Iran's nuclear program, which he had battled relentlessly and unsuccessfully to thwart. Netanyahu's push against the deal exposed a deep rift between Israel and the United States, its most important ally, and opposition lawmakers have called for an inquiry into Netanyahu's failure to prevent it.

Under Netanyahu, Israel also has faced broadening international isolation. A movement calling for a boycott against the country because of its policies toward the Palestinians has been gaining momentum and raising alarm in Israel. Tired of an impasse in peace negotiations, the Palestinians also have opened a diplomatic offensive that has left Israel vulnerable to potential war crimes claims at the International Criminal Court.

Netanyahu's office declined comment on the investigation, though in the past the couple has accused the media of launching a witch hunt against them. When the state comptroller's report was released earlier this year, Netanyahu said there was "certainly no indication of any criminal transgressions."

Over the years, reports have been released about the high cost of the Netanyahus' catering, housekeeping, furniture, clothing and makeup. In one case, the premier was chided for spending $127,000 in public funds for a special sleeping cabin on a flight to London. Even their costly purchases of scented candles and pistachio-flavoured ice cream have been derided.

Opposition lawmaker Karin Elharrar told the Israeli news website Ynet that she plans to summon Netanyahu to a meeting of the parliamentary state control committee, which she heads, to answer the accusations in the comptroller's report.

"I want him to give explanations. The state comptroller's report speaks of behaviour that is, to put it lightly, inappropriate," she said.