Israeli PM Benjamin Netanyahu made "illegitimate use" of his power and saw favours as "currency", a prosecutor has alleged at his corruption trial.
Liat Ben Ari told a court in Jerusalem that he sought "improper benefits from owners of major media in Israel in order to advance his personal affairs".
Mr Netanyahu has denied any wrongdoing.
The hearing comes as Israel's president meets parliamentarians to ask whom they support to form the next government following last month's election.
It failed to end the long period of political stalemate that has led to four elections in two years, leaving both Mr Netanyahu's right-wing bloc and the parties opposed to him remaining in power short of a majority.
Once President Reuven Rivlin has consulted all the parties, he will nominate whoever he thinks has the best chance of forming a governing coalition.
Israeli media cited him as telling members of the Yesh Atid party of opposition leader Yair Lapid: "At the moment, I can't see a way to form a coalition."
Mr Netanyahu's rivals fear that if he remains prime minister he will push through legislation that would grant him immunity from prosecution while in office. He rejects such a claim.
What is Benjamin Netanyahu accused of?
He has been indicted in three cases, known as 1,000, 2,000 and 4,000:
- Case 1,000 - Fraud and breach of trust: he is accused of receiving gifts - mainly cigars and bottles of champagne - from powerful businessmen in exchange for favours
- Case 2,000 - Fraud and breach of trust: Mr Netanyahu is accused of offering to help improve the circulation of Israeli newspaper Yediot Ahronot in exchange for positive coverage
- Case 4,000 - Bribery, fraud and breach of trust: As PM and minister of communications at the time of the alleged offence, Mr Netanyahu is accused of promoting regulatory decisions favourable to the controlling shareholder in the Bezeq telecom giant, Shaul Elovitch, in exchange for positive coverage by Mr Elovitch's Walla news site
Mr Netanyahu has denied all the charges against him, branding them a "witch-hunt" by his political opponents, and has vowed to clear his name.
What happened at Monday's hearing?
Dozens of Netanyahu supporters and protesters demanding his removal from office gathered outside the Jerusalem District Court as the prime minister arrived for the start of the trial's evidentiary stage.
Mr Netanyahu sat with his lawyers as Ms Ben Ari delivered the prosecution's opening statement, describing what she called "a significant and severe case of regime corruption".
"The relationship between Netanyahu and the defendants became currency, something that could be traded," she told the three-judge panel. "This currency could distort a public servant's judgment."
Afterwards, Mr Netanyahu was allowed to leave the courtroom and the first witness, Ilan Yeshua, the former CEO of the Walla news site, took the stand.
Mr Yeshua's testimony is seen as key to Case 4,000, which is considered the most serious against the prime minister because it involves the bribery charge.
Walla's chief executive editor, Aviram Elad, former news director Michal Klein and former head of the news desk Amit Eshel are expected to testify next, followed by former communications ministry director-general Avi Berger.
In February, the judges agreed to a request by Mr Netanyahu for the evidentiary stage to be delayed until after the election. He warned that failing to do so would represent a "crude intervention" in the poll.
Mr Netanyahu also insisted the cases against him were "not even completed fabrications", adding that "lots of things are missing, even from the prosecution's point of view".
How can the PM serve and stand trial?
He is presumed innocent unless proven otherwise, and there is currently no legal barrier to him staying in office as prime minister.
And even if convicted, Mr Netanyahu would not be required to step down until the appeals process is exhausted - something that could take years.
A former prime minister, Ehud Olmert, stepped down as his party's leader when he was under investigation for corruption in 2008 but technically remained in office until elections the following year - polls which brought Benjamin Netanyahu to power.
Mr Olmert was eventually convicted of bribery, fraud, obstruction of justice and breach of trust in connection with several cases. He served 16 months of a 27-month prison sentence.
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