JERUSALEM, Feb. 21 (Xinhua) -- Israeli Prime Minister Benjamin Netanyahu's close associate, Shlomo Filber, has signed a deal to become a state witness in a corruption case, the police said on Wednesday.

Filber, who was the director of the Communication Ministry under Netanyahu, has been under arrest since Sunday.

Under the deal, signed overnight between Tuesday and Wednesday, Filber is expected to incriminate Netanyahu in a bribery case involving Bezeq, Israel's giant telecom company, in exchange for a lighter sentence.

The police confirmed that the deal was signed but did not provide details on its content.

Local media reported the prime minister's long-time confidant is expected to testify that he was instructed by Netanyahu to provide financial and regulatory benefits to Bezeq.

In return, Walla news site, which is controlled by Bezeq, allegedly gave a favorable coverage to Netanyahu and his wife.

The move was the latest in a cascade of revelations on Netanyahu's suspected involvement in corruption that have been rocking the country since Sunday.

As part of the investigation, the police arrested on Sunday Bezeq's control holder, Shaul Elovitch, Bezeq's CEO Stella Handler, as well as Elovitch's son and wife and other senior executives. Nir Hefetz, Netanyahu's former media adviser, was arrested too.

On Tuesday, the police revealed that Hefetz, a close confidant of Netanyahu, allegedly tried to bribe a judge in return for closing a criminal case against Sara Netanyahu.

Netanyahu denies any wrongdoing. He released a video statement on his Facebook page on Tuesday night, denouncing the police. "They are creating new cases every two hours. They bring associates, interrogate them, every associate is questioned, and immediately there is a flood of misleading leaks," he said.

According to Netanyahu, the investigations are part of a conspiracy to topple him. "They are bringing two false, lying claims, as part of the witch hunt against me and against my family which has been going on for years," he said.

"All the decisions regarding Bezeq were made by professional committees, by professionals, under close legal supervision," he said.

The new developments came only a week after the police recommended charging Netanyahu with corruption in two separate cases.

In the first one, dubbed by the police "case 1000," Netanyahu is suspected of receiving expensive jewelry, cigars, and Champaign in return of promoting the interests of Israeli businessman and Hollywood tycoon, Arnon Milchan.

In the second case, dubbed "case 2000," Netanyahu allegedly received bribes from Arnon Mozes, the publisher of Yedioth Aharonoth, one of Israel's largest newspapers in return for positive coverage in Yediot Aharonot.