JERUSALEM, June 9 (Reuters) - A ban on Al Jazeera's operations in Israel was extended for another 45 days by Israel's telecoms regulator on Sunday after the cabinet agreed its broadcasts posed a threat to security.

A Tel Aviv court last week upheld an initial 35-day ban on Al Jazeera operations in Israel, imposed by the government on national security grounds, which ended on Saturday.

In a separate ruling on a petition by Al Jazeera against the closure, Israel's Supreme Court described the measure against the Qatari-backed broadcaster channel as "precedent-setting".

It gave Israel's government until Aug. 8 to offer arguments for "why it should not be determined that the Law Preventing a Foreign Broadcaster from Harming National Security" is void.

Al Jazeera had told the court it did not incite violence or terrorism and that the ban was disproportionate, court documents showed. The channel, which has criticised Israel's military operations in Gaza, was not immediately available for comment.

The network's broadcasts on the cable and satellite companies and access to its websites will remain blocked, Israel's Communications Ministry said.

"We will not allow the terrorist channel Al Jazeera to broadcast from Israel and endanger our fighters," said Shlomo Karhi, adding that the law authorised him as communications minister to take such action against foreign broadcasters.

"In light of the seriousness of the damage to the security of the state I am convinced that the closure orders will be extended in the future as well," he said.

Judge Shai Yaniv had said he had been provided with evidence, which he did not specify, of a long-standing and close relationship between the Palestinian Islamist group Hamas and Al Jazeera, accusing the channel of promoting Hamas' goals.

Israeli authorities raided a Jerusalem hotel room used by Al Jazeera as its office on May 5 and said they were shutting the operation down for the duration of the Gaza war. (Reporting by Steven Scheer; Additional reporting by Dan Williams; Editing by Alexander Smith)