Israeli police made dozens of arrests on Monday as part of a vast investigation into suspected corruption at the country’s main labor union.

Founded in 1920 in British-mandate Palestine, the Histadrut union has more than 800,000 members and plays a key role in Israeli society.

“This morning, detectives from Israel Police’s Lahav 433 National Fraud Investigations Unit arrested and detained dozens of suspects on suspicion of bribery, fraud and breach of trust, money laundering, and tax offences,” a police statement said.

“The covert investigation, conducted over the past two years, focuses on senior officials within the Histadrut, local authorities, and government companies and corporations, who are suspected of receiving bribes and benefits from business figures in exchange for advancing their interests and generating financial gain,” it added.

Israeli media reported that Histadrut’s president, Arnon Bar-David, was arrested as part of the probe.

Opposed to the policies of Prime Minister Benjamin Netanyahu, Bar-David had called for a general strike after the dismissal of defense minister Yoav Gallant in March 2023.

He later renewed his threats of strike action during the war in Gaza to demand that the government reach an agreement for the release of hostages held there by militants.

Histadrut responded to the arrests in a statement saying it was “convinced of the innocence of our employees”.

“We are cooperating with the authorities... Histadrut’s activities in the public service are continuing as normal,” the statement added.

The mayor of the southern city of Kiryat Gat, Kfir Swisa, who is also a member of Netanyahu’s Likud party, on Monday said he was being questioned by police in connection with the case.