Sydney  - Over 100 prominent Australian Jews issued an open letter Tuesday describing Israel's Gaza siege as "grossly disproportionate" to the threat posed by Hamas' rocket attacks.

The group Independent Australian Jewish Voices accused Israel of breaking its truce with Palestinian militant groups in Gaza.

"There is a growing number of Jews around the world, tens of thousands if not more in the last week, if nothing else have spoken out forcefully against Israel," spokesman Antony Loewenstein said.

"Yes, we believe Israel has the right to security, that goes without saying, but the fact is that Australian Jews, and any other Jew in the world, any other citizen for that matter, has the right to speak out."

The condemnation came as Prime Minister Kevin Rudd defended Israel's right to defend itself from rocket attacks.

"Australia recognizes Israel's right to self-defence," Rudd said.

Those grouped in Jewish Voices were criticized as "grossly ill- informed" by Colin Rubenstein, head of the Australia/Israel and Jewish Affairs Council.

"They propose that the population of southern Israel must continue to live under constant rocket bombardment, opposing all practical efforts to actually invoke the right to self-defence the signatories say they recognize," Rubenstein said. (dpa)