A Haaretz journalist who returned to Israel on Monday to face questioning over leaked military documents received no guarantee of immunity, the prosecutor in the case said Tuesday.

Uri Blau flew into Tel Aviv from London after nearly a year abroad for questioning under caution by both the Shin Bet security service and police.

State prosecutor Mibi Mozer told Army Radio that although Blau had returned following an agreement with the Shin Bet, he had been given no assurance he would avoid criminal charges for publishing classified materials he received from Anat Kamm, a former soldier.

The deal for Blau's return "struck a proper balance between national security and freedom of the press", Mozer said, adding that although Blau would be asked to hand over documents, the journalist's sources would be protected.

"The fact that Uri will be forced under the terms of the bargain to hand over hundreds of documents to the security services, including those he received from Anat Kamm, does not constitute an infringement of press freedoms, as the Shin Bet has undertaken not to investigate their sources," Mozer said.

Blau's defense attorney, Talya Lieblich, said the deal served both sides. "Both national secuirty and press immunity won here," she said.

Blau had been on vacation when he learned that the state might press charges against him and decided to delay his return as a result.

He had been in London and Berlin.

The results of the interrogation will be presented to Attorney General Yehuda Weinstein, who will decide whether Blau will face criminal charges.

He used the documents to write articles for Haaretz, which were published after receiving approval from the censor. The documents included orders by then-GOC Central Command Yair Naveh instructing soldiers to carry out a targeted assassination in violation of a Supreme Court verdict.

Blau said he no longer has any documents from Kamm, in any format, the Justice Ministry said. He also agreed to undergo a polygraph test.

When the article about the assassination was published, the state asked Blau to return the original documents. Blau obliged, after officials promised they would not be used as part of a criminal investigation against him or his source.

Following a Shin Bet investigation, however, Kamm admitted to have been the source, and said she took more than 2,000 classified documents during her army service. She gave most of them to Blau.

Kamm was charged with possession and transfer of classified information with the intent to harm state security, a crime considered grave espionage and punishable by life in prison.

Under the negotiations, and after Kamm waived her immunity as a journalistic source, Blau gave the state 1,500 documents he received from Kamm.