A criminal investigation could be launched into Israeli Prime Minster Benjamin Netanyahu in the next few days, local media reports suggest.

The country's Attorney General Avichai Mandelblit has already conducted an extensive inquiry into allegations of corruption, money laundering and bribery into Netanyahu since July.

However, according to Israel's Channel 2, Mandelbilt has received new information to escalate the inquiry into a full-blown criminal investigation.

Among the allegations are that Netanyahu accepted large sums of money from convicted French fraudster Arnaud Mimran. In July, Mimran was jailed for eight years and fined €1m (£850,000) for carbon-tax fraud in what French media described as "sting of the century".

Netanyahu is also accused of using state money for personal jaunts, with his wife and children. Last year, he went on a six-day trip to New York dipping into $600,000 (£462,000) of state funds – which included spending $1,600 on a personal hairdresser.

However, a spokesman for the prime minister has labelled all the claims as baseless.

In a statement sent to Haaretz, the spokesman said: "It's all idle chatter. Since Netanyahu's victory in the last election and well before that, forces hostile to the prime minister have made enormous efforts to topple him, hurling false accusations against him and against his family.

"It is all lies. There never was nor will there ever be anything."

Since the investigation into Netanyahu began, his ally David Amsalem has proposed legislation in the country's parliament, the Knesset, which proposes to give the prime minster immunity for "minor offences".

He claims the prime minster has been dogged by malicious investigations, rather than be allowed to get on with his job, but has come under severe criticism for trying to whitewash Netanyahu's crimes.

Nachman Shai, from the Zionist Union, said the Likud party – which both Netanyahu and Amsalem are a part of – is trying to undermine the rule of law for its political advantage.

"No one in Israel is above the law, not this prime minister, not his predecessors and not those who come after him," Shai said.