JERUSALEM — Israel threatened Monday to pull out of a U.N. inquiry into a deadly raid on a Turkish flotilla heading for Gaza, after the U.N. chief said there is no agreement that the panel would refrain from calling Israeli soldiers to testify.

Last week Israel agreed to participate in the U.N. probe into the May 31 raid, when nine pro-Palestinian activists were killed after Israeli naval commandos boarded a Turkish vessel aiming to break Israel’s sea blockade of Gaza.

The surprise development came just hours after Israeli Prime Minister Benjamin Netanyahu testified before his country’s own inquiry into the raid. He charged that Turkey had an interest in the violent confrontation, refusing to exert its influence to stop the flotilla.

Israeli officials said the agreement to take part in the U.N. probe was conditional on the panel relying on reports from Israel’s own military inquiry, not testimony from soldiers.

But at a Monday news conference at U.N. headquarters, Secretary-General Ban Ki-moon was asked whether he had agreed not to summon Israeli soldiers before the panel.

“No, there was no such agreement behind the scenes,” Ban said.