As speculation grows about an Israeli attack on Iran, and its potential consequences, the Jewish state's home front defence minister Matan Vilnai is leaving his post -- to become ambassador to China.

Israeli Prime Minister Benjamin Netanyahu confirmed on Sunday that Vilnai will be the next ambassador in Beijing, an appointment he said was "of national importance."

"We want to significantly increase commerce and economic ties with the rising powers of the East, first and foremost China," he said on Sunday, ahead of a cabinet meeting.

But Vilnai's appointment leaves empty the top post at the home front defence ministry, and officials said it was unclear who would replace him, or whether the ministry would even continue to exist as a separate entity.

The home front defence ministry was created as a separate department last year, in part in response to the perceived home front protection failures during Israel's 2006 war with Lebanon's Hezbollah.

Vilnai's departure, which his spokesman said could take place any time between April and August of this year, comes as speculation grows on whether Israel is planning a military operation against Iran's nuclear facilities.

Israel and much of the international community suspect Iran's programme masks a drive for weapons, a charge Tehran denies.