Washington - Presumptive Republican nominee John McCain said Monday the United States must increase support for Israel while encouraging the world to remove investments from Iran, which he labelled as the biggest threat to the Jewish state.

"The threats to Israel's security are large and growing, and America's commitment must grow as well," McCain told a pro-Israel lobbying group in Washington.

"I am committed to making certain Israel maintains its qualitative military edge," McCain told the American Israel Public Affairs Committee, or AIPAC.

The Arizona senator criticized Iran's support of Hezbollah and Hamas, calling Tehran the "world's chief sponsor of terrorism." Iran's alleged pursuit of nuclear weapons threatens the world, McCain said, while blasting Iranian President Mahmoud Ahmadinejad for controversial remarks about Israel and the Holocaust.

"Foremost in our minds is the threat posed by the regime in Tehran," McCain said.

McCain said the United States should step up pressure on other countries to divest from Iran and use their political leverage to isolate the Islamic state.

"Rather than sitting down unconditionally with the Iranian president or supreme leader in the hope that we can talk sense into them, we must create the real-world pressures that will peacefully but decisively change the path they are on," McCain said, taking a jab at the leading Democratic nominee, Barack Obama.

Obama has suggested he would hold unconditional talks with Iran's leadership. (dpa)