Israeli Prime Minister Ehud Olmert, whose political future has been thrown in doubt by a police probe into corruption allegations, will make a statement from his official residence on Wednesday, his office said.
It was unclear whether the surprise announcement would be related to the investigations, to peace talks with the Palestinians and Syria, or another issue.
The announcement comes a day after Olmert's centrist Kadima party said it had scheduled a leadership vote on Sept. 17, an election that could lead to Olmert's ouster. Olmert has not said publicly whether he intends to run.
The two most prominent investigations involve suspicions that Olmert took bribes from an American businessman, and charges he submitted duplicate claims for travel expenses in a former capacity as trade minister and mayor of Jerusalem.
Olmert has denied wrongdoing with respect to the police probes, but has said he would resign if indicted.